Sinking of MV Sewol

Background

At the time of her purchase by Chonghaejin Marine in 2012, the ship that would come to be known as the Motor Vessel (MV) Sewol was 18 years old and dilapidated. She was first named Ferry Naminoue and was operated from 1994 to 2012 as a transport ship for cargo and passengers by the Japanese company A-Line Ferry. According to A-Line Ferry, she did not experience any problems while being operated by the company in Japan. After she was purchased on 8 October 2012, she was registered by Chonghaejin on 22 October 2012 and underwent modifications from 12 October 2012 to 12 February 2013. The modifications were later found to have been based on an illegal redesign of the ship.

After the modifications, which included the addition of two floors of passenger space and the expansion of the cargo space, Sewol had her gross tonnage increase by 239 tons to 6,825 tons and her persons capacity increase by 116 people for a total of 956 people including the crew. The modifications also resulted in her center of gravity being moved upward by .51 m (1 ft 8 in) as well as a left-right imbalance. After the modifications were completed, she underwent investigations by the Korean Register of Shipping including an inclining test, and received the ship inspection certification and the certification for the prevention of sea pollution on 12 February 2013. During the process of approving the modifications, the Register reduced the maximum amount of cargo that could be carried by 1,450 tons to 987 tons, and increased the amount of ballast needed by 1,333 tons, to 1,703 tons. However, the cargo limits were not known by the Korea Shipping Association, who has the responsibility to manage ferries, or the Korea Coast Guard, who were responsible for overseeing the Shipping Association. The South Korea government's Audit and Inspection Board later revealed that the Register's licensing was based on falsified documents. After the inspections, 37 tons of marble were further added to the gallery room at the bridge deck located on the back of the ship.

Sewol began operations on 15 March 2013. She made three rounds trips per week from Incheon to Jeju, each one-way voyage of 425 kilometres (264 mi) taking 13.5 hours to complete. On 19 February 2014, she received an interim inspection and a periodic inspection from the Register. She had made the round trip a total of 241 times until the day of the incident.

On 15 April 2014, Sewol was scheduled to leave the port at Incheon on 6:30 p.m., Korea Standard Time. However, a fog which restricted the visible distance to less than 1 kilometre (0.62 mi) led the Incheon vessel traffic service (VTS) to issue a low visibility warning around 5:30 p.m., leading the Shipping Association to stop the departing of the Sewol. The VTS retracted the warning around 8:35 p.m., and the Shipping Association removed the restriction on Sewol's departing after checking the weather conditions with the operator of the Palmido lighthouse and consulting with the Korean Coast Guard. She departed around 9 p.m., and was the only ship to leave port that evening.

When she departed, she was carrying 443 passengers, 33 crew members, and a total of 2,142.7 tons of cargo including 185 cars. 325 of the passengers were students on a field trip from Danwon High School and five passengers did not have a Korean nationality. The ship was commanded by 69-year-old Captain Lee Joon-seok who had been brought in as a replacement for the regular captain. He had over 40 years of experience at sea, and had traveled over the route before. He was hired on a one-year contract, with a monthly salary of ₩2.7 million. Lee worked with 33 crew members for the journey, out of which 19 were irregular, part-time workers.

Later investigations discovered problems concerning the state of Sewol at the time of departure. The Safety Investigation Report made by the Korea Maritime Safety Tribunal noted that Sewol at the time of departure was carrying 2,142.7 tons of cargo when its maximum allowance was 987 tons. TIME magazine further noted that the cargo has been improperly secured. The Report also noted that only 761.2 tons of ballast were taken on board, that some ballast tanks have not been properly maintained, and that the last voyage was made without making further adjustments to the ballast during the journey. Kukmin Ilbo reported that Captain Shin, the regular captain of Sewol, had warned the company about the decrease in stability and passenger satisfaction and attributed it to the removal of the side ramp. However, Captain Shin claimed that the company responded by threats to fire him if he continued the warnings. Captain Shin's warnings were also relayed through an official working for the Incheon Port Authority on 9 April 2014, which an official from the company responded to by stating that he would deal with anyone making the claims. The Korea Herald also reported that the captain had requested a repair for the malfunctioning steering gear on 1 April 2014, which was not done. The Daily Telegraph reported that the Korean Register of Shipping had noted in a stability test report dated 24 January 2014 that Sewol had become 'top heavy and less stable after modifications were made.' The New York Times reported that the company budget for the safety training of the crew was $2 USD, which was used to buy a paper certificate.

Entering the Maenggol Channel (07:30–08:46)

On 16 April at 7:30 a.m. (KST), third mate Park Han-kyul and helmsman Cho Joon-ki took over the watch from the previous team. At this point in time, Sewol was heading at a course of about 165 degrees at the speed of about 20 knots, and was operating two radar devices. Around 8:20 a.m. when the ship was about 2-3 miles from entering the Maenggol Channel, Park ordered Cho to change the steering system from autopilot to manual steering. When Sewol arrived at the channel on 8:27 a.m. at a course of around 137 degrees, the wind speed was between 4 and 7 meters per second, the wave height about 0.5 meters, and the visibility good.

The Maenggol Channel has strong underwater currents, which necessitate caution when steering a ship through the channel. At the time of the incident, conditions were calm and Sewol was following a route that was frequently used. While the wider areas of the channel contains rock hazards and shallow waters, they were not in the immediate vicinity of the ship's usual path. While prosecutors and some news organizations including CNN and The Chosun Ilbo labeled Park as being 'inexperienced' based on her unfamiliarity with the channel, the Safety Investigation Report noted that Park had in multiple occasions passed through the channel on another ship.

As Sewol approached the fatal turn, breakfast was being served in the cafeteria. Seong-mok Kim, a passenger, later recalled having eaten breakfast right before the incident. CCTV data taken at 8:40 a.m. also showed students present and socializing on the deck. Another passenger, Eun-seun Choi, recalled having gone up to the deck to smoke right before the incident.

Multiple turns to the right (08:48)

Right before the incident, the Chief Engineer, Helmsman Cho, and Third Mate Park were standing side by side near the ship's wheel at the bridge. Captain Lee was absent from the bridge at the time. At 8:46 a.m., Sewol was travelling at a speed of 18 knots at a course of around 136 degrees. At this time, Park ordered Cho to change the course from 135 degrees to 140 degrees, which Cho consequently undertook.

There are conflicting accounts of what happened next. According to Park's testimony, after she has used the radar to check that Sewol's course was changed and the current course was set to 140 degrees, Park ordered Cho to change the course of the ship further to 145 degrees. The order was given at 8:48 a.m. However, after realizing that the ship was heavily inclining to the left which led the bow to turn to the right, she gave an order to turn the wheel to 'port.' Immediately after giving the order, she heard Cho exclaim "the wheel isn't working" in a flustered voice, after which the ship started inclining. The testimony of the Chief Engineer did not notably differ from that of Park.

However, Cho testified that the inclining of the ship began with the order to turn to 140 degrees. According to Cho, he only received the order the change the course to 140 degrees, and not the order to change the course to 145 degrees. Because the ship kept turning towards the right even as he was holding onto the wheel, he made two turns to the left amounting to a 5 degrees turn. However, because the ship did not stop the turns, the ship eventually faced the course of 145 degrees. Cho testified that Park gave an order to turn 'in the opposite direction' at this point, which he followed by turning the ship further to the left by 10 degrees, so the total amount of the turn became 15 degrees to the left.

The court came to the conclusion that Cho's steering led the ship to attempt a 15 degree turn for 40 seconds. The court concluded that Cho, who was flustered by the ship turning faster than expected when he was following Park's order to turn to 145 degrees, was attempting to turn to the left when he took Park's order to mean a turn in the opposite direction. This led him to make a turn to the right, causing the head of the ship to rapidly turn right.

Effects of the turn

Later analysis of Sewol's track chart by the Ministry of Oceans and Fisheries revealed that the ship's Automatic Identification System had stopped collecting data from 8:48:37 to 8:49:13; consequently, the Ministry and the Jindo Vessel Traffic Service (VTS) lost 36 and 29 seconds of data, respectively. While earlier reports and investigations believed that there was a power outage, Huh Yong-bum, the head of the expert advisory panel on the police-prosecution joint investigation team, testified that the AIS failure was due to system limitations and that the failure did not affect the steering.

According to the joint investigation team, the sharp turn was a combined result produced by the steering error and the lessened restoring force caused by overloading; investigations did not show any malfunctions with the generator or the battery. From 8:49:26, AIS data showed Sewol's angular velocity accelerate from 0.29 radians per second to 0.83, 1.00, and 2.00 until 8:49:39; these readings were consistent with previous testing data gained from earlier tests conducted on an empty Sewol. Consequently, the ship herself listed 20 degrees into the water; on 8:49:40, causing cargo to fall to one side of the ship. The impact caused the ship's gyroscope to erroneously record angular velocities of 15 radians per second on 8:49:40, 14 on the next second, and −11 on the consequent second, and tilt the ship 10 degrees further into the water. Passengers also reported hearing a loud "bang."

As Helmsman Cho sharply turned the wheel from 135 to 150 degrees, Sewol began to list to port and tilt towards the water. The overall effect was that the ship turned about 45 degrees to the right, then rotated 22 degrees on the spot for a span of 20 seconds. The cargo falling to one side of the ship caused Sewol to lose all her restoring force and allowed water to flow into the ship through the side door of the cargo loading bay and the car entrance located at the stern. This scenario was confirmed by simulations separately run by the expert advisory panel on the joint investigation team, the Korea Research Institute of Ships and Ocean Engineering, and the Advanced Marine Engineering Center of Seoul National University. The chief engineer testified that the tilting lasted for about two to three minutes after the initial tilt. During this time, Oh Yong-seok, an off-duty helmsman who was sleeping in his cabin, was awakened when he was thrown against its port side. As of 8:50 a.m., Sewol was leaning 30 degrees to port.

Captain Lee, who was in his private cabin at the time of the incident, immediately rushed to the bridge. After a short period, all the ship's mates and helmsmen arrived there as well. Around this time, the chief engineer stopped the engines, although it is unknown whether it was on his own volition or following an order from Captain Lee. At 8:50, the chief engineer ordered an evacuation of the engine room through a call to the assistant engineer. During this time, Park was crying, as she was taken aback by the sudden incident; this lasted until at least 9:06 a.m.

With the engines off, Sewol became unable to change directions and began drifting sideways. A passenger later testified that lights went out after the ferry started listing.

Calls for rescue (8:52–9:30)

As Sewol began sinking, the ferry's intercom system started ordering the passengers to stay put, alleging that moving was dangerous. The announcements were made by a communication officer, Kang Hae-seong, who had not consulted the manual before the broadcast. The announcements began broadcasting by at least 8:52 a.m. and continued even when water began flooding passenger compartments. Other crew members corroborated this order, instructing passengers to stay put. Captain Lee also instructed passengers to stay put and did not change the order even as he was leaving the ship.

The first emergency call was made by Choi Duk-ha, a Danwon high school student aboard the ferry. At 8:52 a.m., he called the national emergency service number and reported to the Jeollanam-do fire station that Sewol was capsizing. Choi was connected to the Mokpo Coast Guard at 8:54 a.m. and was asked to give the latitude and longitude of the ship's location. Three minutes later, the Mokpo Coast Guard station situation room ordered patrol vessel No. 123 to be dispatched to the scene; the vessel was launched at 8:58 a.m. Following the Coast Guard search and rescue manual, the boat was to be in charge of surveying the area and "swiftly" rescuing passengers. Choi did not survive the capsizing and was later found dead.

At 8:55 a.m., Sewol's crew made their first distress call to the Jeju vessel traffic service and asked the Jeju VTS to notify the Coast Guard, as the ferry was rolling and in danger. At 8:56 a.m., the Jeju VTS called the Jeju Coast Guard. Three minutes later, the Jeju Coast Guard called the Mokpo Coast Guard and discovered that a patrol boat had already been dispatched. At 9:01 a.m., a crew member on Sewol called the Incheon branch of Chonghaejin Marine to report the situation, and the Chonghaejin Marine headquarters located in Jeju then called Captain Lee at 9:03 a.m. for a report of the situation. The Incheon branch then talked with the first mate in five telephone calls over the next 35 minutes.

At 9:06 a.m., the Jindo VTS were informed of the capsizing incident by the Mokpo Coast Guard. Around this time, the crew began communicating with the Jindo VTS, which was closer to their location. For the next two minutes, Jindo VTS alerted two other ships that Sewol was sinking, with one confirming that it had visual contact with the ship. At 9:07 a.m., Sewol's crew confirmed that the ferry was capsizing and requested the help of the Coast Guard. At 9:14 a.m., the crew stated that the ship's angle of heel made evacuation impossible. Around this time, the captain of Patrol Vessel 123 was appointed the commander of the scene. Four minutes afterwards, the crew of Sewol reported to the VTS that the ferry had heeled more than 50 degrees to port.

At 9:23 a.m., the VTS ordered the crew to inform the passengers to wear personal flotation devices. When the crew replied that the broadcasting equipment was out of order, the VTS told them to personally order the passengers to wear life jackets and more clothing. At 9:25 a.m., the VTS asked the captain to decide quickly whether to evacuate the ship, stating that they did not have enough information to make the decision. When the captain inquired about the rescue, the VTS replied that patrol boats were due to arrive in 10 minutes and a helicopter in one minute. The captain then replied that there were too many passengers for the helicopter.

During this time, the captain told passengers to stay in their rooms. The communications officer, using the ship's intercom, repeatedly ordered passengers not to move.

Around 9:30 a.m., the captain gave orders to evacuate the ship, though the order may not have been relayed to all the passengers. At 9:33 a.m., after confirming that nearby ships had volunteered to help in the rescue operations, the VTS told all ships to drop lifeboats for the passengers. At 9:38 a.m., all communications were cut off between the VTS and the ferry. About three minutes after all communications were cut, about 150 to 160 passengers and crew jumped overboard.

Sewol took two and a half hours to sink. By around 11:18 a.m., the bow of the ship was submerged, with a section of the hull about 2 metres (6 ft 7 in) high and 20 to 30 metres (66 to 98 ft) long showing above the water. At 12:00 noon on 18 April, only 50 centimetres (20 in) of the bulbous bow was above water. As of 1:03 p.m., the ship was completely submerged.

Captain and crew

During the capsizing, some members of the crew drank beer. The crew also had seven phone calls with staff from Chonghaejin Marine. As passengers stayed in their cabins as instructed, the captain and crew members abandoned the ship. The captain, the chief engineer, and the chief and second mates were the first people to be rescued. The captain was rescued around 9:46 a.m.

Passengers

As the ship capsized, some passengers followed the announcements to stay put, even as the water came in. Most of the student passengers obeyed the announcements. Some passengers who climbed to the top of the ship or jumped into the water were rescued.

Videos recording passengers during the capsizing have been recovered. Some recorded the announcements telling passengers to stay in place and put on life jackets, while some showed passengers joking around, putting on life jackets, and sending farewells.

Passengers made calls, sent text messages, and KakaoTalk mobile messages during the capsizing. The last message was sent at 10:17 a.m. Text messages and social media posts allegedly made by survivors after the capsizing have circulated in the media, but an investigation by the Cyber Terror Response Center found that passengers did not use their phones between 12:00 p.m. on 16 April and 10:00 a.m. of 17 April and that all the reported survivors' messages were fake.

Rescue operations

During the capsizing and the subsequent reporting, the government's announcements, as well as the media, have been inconsistent and inaccurate. An editorial in The Huffington Post stated that the governmental reports were like a rubber band, 'increasing at one moment and decreasing at another.' Newspapers such as The JoongAng Ilbo, MBN, and JTBC have made corrections and apologies concerning their earlier reports. Conspiracy theories have also been present.

First day

At 8:58 a.m. (KST) on 16 April 2014, the Mokpo Coast Guard dispatched patrol vessel No. 123 in response to the first report of the incident. After receiving the news of the capsizing from the Jeollanam Provincial Government, the Republic of Korea Navy 3rd Fleet sent a Gumdoksuri-class patrol vessel (PKG) to the accident site at 9:03 a.m.; the Navy dispatched another PKG at 9:09 a.m. At 9:04 a.m., the government created the Central Disaster Countermeasure Headquarters (중앙재난안전대책본부), as an organization which would directly report to the government. The South Korean coast guard set up a rescue operations headquarters at 9:10 a.m.

Patrol vessel No.123 arrived at the scene near 9:30 a.m. as the first ship to reach the site after the incident. During the time between the dispatch and the operations, members failed to raise Sewol, and chose to call for other ships on the radio. Consequently, members on the vessel had not directly communicated with Sewol, and were not aware of the content of the communication between Sewol and the Jindo VTS on arrival. At the time of arrival, Sewol had listed about 50 to 60 degrees to port. When the vessel arrived, members made announcements for five minutes, calling people to abandon ship and jump into the water. The vessel began rescue operations at 9:38 a.m., with the dispatching of a rubber boat. Passengers who had reached the deck or jumped into the water were rescued, including the captain, but rescue members could not get inside the ship due to the list. However, people trapped inside the pilothouse were rescued by breaking through the windows.

At 9:35 a.m., the Korean Ministry of National Defense started operating Counter-disaster Headquarters (재난대책본부). At 9:40 a.m., the Ministry of Oceans and Fisheries declared the accident to be the highest state of emergency in terms of naval accidents; consequently, the Central Accident Response Headquarters (중앙사고수습본부) was established. At the same time, the Ministry of Health and Welfare sent emergency vehicles and the first squad of the Disaster Medical Support Team (재난의료지원팀) to Jindo. At 11:28 a.m., the Korea Navy's Ship Salvage Unit (SSU) was reported to have been deployed for the operations.

At 2:42 p.m., 150 special forces personnel from the ROK Army Special Warfare Command, including 40 scuba divers, were sent for the operation. At this point, 196 personnel, including 82 in the SSU and 114 in the ROK Naval Special Warfare Flotilla were involved in the operations. At 3:07, the regional government of the Gyeonggi Province was reported to have started operating the Prevention and Countermeasures Headquarters (재난안전대책본부). After 5 p.m., units from the SSU began undersea operations. At 5:13, the Gyeonggi-do Office of Education was reported to have started operating the Ansan Danwon High School Accident Countermeasures Report Compiling Headquarters (안산 단원고 사고대책 종합상황본부). At 8:00, operations investigating the ship's hull were ceased.

As of 22:03, the following units were involved in rescue operations: Naval forces include sailors from the 3rd Fleet (제3함대; 第三艦隊), a Dokdo-class amphibious assault ship, a Chungmugong Yi Sun-sin-class destroyer, and an Ulsan-class frigate. The ROK Air Force sent support units such as the Lockheed C-130 Hercules, Sikorsky HH-60 Pave Hawk, and HH-47 variant of the Boeing CH-47 Chinook. The ROK Army sent units including 150 Special Warfare Command soldiers and 11 ambulances.

Second day

Starting on 17 April, Undine Marine Industries Co., a privately held company, began to lead the search for missing passengers. At 12:30 a.m., hull investigations were started by the ROK Coast Guard with the help of flares. As of 6:00 a.m., 171 ships, 29 aircraft and 30 divers were involved in the rescue effort. The Korea Coast Guard had assigned 20 divers in teams of two. The ROK Navy had also assigned 8 divers. However, the coast guard prevented navy divers from participating while waiting for divers from Undine Industries. At 7:24 a.m., civilian groups of expert divers were reported to be helping out in the rescue operations. During the morning, the number of divers involved in the operations reached 555. The Navy also established a military control tower on a Dokdo-class amphibious assault ship. Starting around 2:00 p.m., rescue operations were practically stopped due to bad weather conditions. A marine crane arrived on the scene at night.

Subsequent operations

At 10:50 a.m. on 18 April, the ROK Coast Guard began pumping in air to support possible air pockets. At the same time, divers entered the capsized ship's hull but only gained access to the cargo deck. The divers' entrance was later labeled a 'failure' by the Central Disaster Countermeasure Headquarters. On 19 April, a Navy petty officer who was injured during rescue operations died. On 21 April, remotely operated underwater vehicles began to be used for operations. On 24 April, the CR2000 'Crabster' robot was sent to the rescue site. On 6 May, a diver working for Undine Marine Industries died during the search. This was followed by another diver's death on 30 May. On 17 July, a firefighting helicopter returning from rescue operations crashed near an apartment complex, killing all five officers aboard and injuring a high school student.

The South Korean government announced on April 22, 2015 that it had approved plans to salvage the wreckage of Sewol in hopes of finding more information about the sinking and recovering the bodies of the nine victims still missing. The plan was initially put forward by President Park Geun-hye, and was endorsed by the Minister of Public Safety and Security, Park In-yong. The operation is expected to take as long as 18 months and to cost between $91 and $137 million.

Survivors and casualties

At 11:01 a.m., Munhwa Broadcasting Corporation (MBC) began reporting that all students had been rescued; this news was re-reported by other news organizations, and continued until 11:26 a.m. Around 11 a.m. (KST), officers working for the educational departments for the Gyeonggi Province sent text messages to the students' parents stating that all students had been rescued. The officers' belief was apparently confirmed by a police officer in the Danwon Police Department. Initial reports stated that rescuers retrieved 368 people from cold waters as the passengers, mostly students, had jumped overboard when the vessel started sinking; the South Korean government later corrected this statement, saying 295 passengers remained missing. 22 of the 29 crew survived, including 15 responsible for the navigation.

Early in the rescue efforts, a 27-year-old female crew member was found dead inside the sinking vessel and a male high school student died shortly after arriving at a hospital.

In its April 17 morning edition, The Chosun Ilbo reported that 174 people had been rescued, 4 had died, and 284 were missing. According to CNN and its affiliate YTN, six people died. News1 Korea reported that, as of 8:00 a.m. on April 17, 179 people had been rescued, 6 had died and 290 were missing. Three more people were found dead at 11:00 a.m. and the confirmed death toll rose to 9. At 10 p.m., Yonhap news confirmed that the death toll had risen to 14. By the morning of 18 April, the death toll had risen to 28. On April 19, the death toll rose to 36. By 20 April, the death toll reached 49. By 6 May, a diver searching the sunken ferry had died; not including the diver, the death toll in the ferry disaster rose to 264, with 38 people still missing. By 10 May 2014, the death toll reached 275, with dozens more still missing. By 21 May, the death toll had risen to 288, leaving 16 missing. As of 21 May, the 16 missing were 7 Danwon High School students, 3 Danwon High School teachers, 4 other passengers, and 2 cabin crew members. On 5 and 6 June, one dead passenger and one dead cabin crew member were found, bringing the casualty count to 290, while the number of missing passengers was reduced to 14. By 9 June 2014, a 28-year-old female Danwon High School teacher as well as a 17-year-old male Danwon high school student were found bringing the death toll to 292 and leaving 12 missing. On 24 June, the body of a female student was recovered bringing the death toll to 293 and lowering the missing to 11, including 5 Danwon High School students. The death toll stands at 294 as of 22 July 2014, with 10 missing; the date marked the recovery of the last cabin crew member.

The sinking of Sewol is the deadliest ferry disaster in South Korea since 14 December 1970, when the sinking of the ferry Namyoung killed 326 out of the 338 people aboard.

Foreign response

Direct causes

As of 17 April 2014, the ROK Coast Guard concluded that an "unreasonably sudden turn" to starboard, made between 8:48 and 8:49 a.m. (KST), was the cause of the capsizing. According to the Coast Guard, the sudden turn caused the cargo to shift to port, causing the ship to list and to eventually become unmanageable for the crew. The existence of the sudden turn has been confirmed by the analysis of the ship's Automatic Identification System data. The crew of the ferry has agreed that the main cause was the sudden turn. Experts such as Lee Sang-yun (Korean: 이상윤), a professor and head of the environment/maritime technology institute of the Pukyong National University, have also agreed.

Overloading and improperly secured cargo are also being seen as direct causes. MV Sewol was carrying 3,608 tons of cargo, more than three times the limit of 987 tons. It is estimated that the actual cargo on the day of the accident weighed 2,215 tons, including 920 tons of trucks, cars and heavy equipment, 131 tons of containers and 1,164 tons of general goods. The cargo included building materials destined for naval bases on the island of Jeju.

The overloading was also previously noted by an off-duty captain and the first mate. Lee Sang-yun also proposed overloading as a cause. According to the off-duty captain of Sewol, the ship owners ignored his warning that the ship should not carry so much cargo because she would not be stable.

Sewol was carrying only 580 tons of ballast water, much less than the recommended 2,030 tons; this would make the vessel more prone to list and capsize. South Korean newspaper The Chosun Ilbo argued that the discharging of ballast water was a cause of the incident. The crew had reportedly pumped out hundreds of tons of ballast water from the bottom of the ship in order to accommodate the additional cargo.

Secondary causes

Secondary causes also contributed to the capsizing of the ferry by decreasing the restoring force. The crew of the ferry stated that the lack of restoring force was a cause of the disaster. The Prosecution/Police Coalition Investigations Headquarters (검경합동수사본부) is currently investigating secondary causes which could have lessened the ship's restoring force.

Renovations which added extra passenger cabins have been proposed as a main secondary cause by Kim Gill-soo (Korean: 김길수), a professor in the maritime transport technological department at the Korea Maritime University. This possible cause has also been supported by the captain, as well as Lee Sang-yun.

Explosion

Gong Gil-young (Korean: 공길영), a professor of aviation engineering at Korea Maritime University, commented that the sudden turn was simply the 'first cause' and that there were secondary causes to the incident. He advocated an explosion as the most probable secondary cause.

Reef collision

At the beginning of the investigation, the ROK Coast Guard thought that the cause was a collision with a reef, believing this likely because the area was foggy. The captain denied this was the cause of the accident, and a reef collision has been dismissed as a cause by consensus among experts. The theory is also not currently advocated by the Coast Guard.

Captain and crew

On 19 April, the captain of the ferry was arrested on suspicion of negligence of duty, violation of maritime law and other infringements. The captain had abandoned the ship with passengers still aboard the ferry, while South Korean law explicitly requires captains to remain on the ship during a disaster. Two other crew members, a helmsman and the third mate, were also arrested on that day on suspicion of negligence and manslaughter. By 26 April, twelve further arrests had been made with the whole crew responsible for navigation in detention.

On 15 May, Captain Lee Jun-seok, First Mate Kang Won-sik (who was responsible for managing the ship's ballast), Second Mate Kim Young-ho, and Chief Engineer Park Gi-ho were indicted on charges of Homicide through gross negligence (also described as murder), which carry a potential death penalty. The other eleven crew members face lesser charges of abandoning the ship and ship safety offences.

Three crew members, Park Ji-young, Jeong Hyun-seon, and Kim Ki-woong, are credited by survivors with staying aboard the ferry to help passengers escape. All three went down with the sinking vessel.

Operators

On 8 May, the chief executive of Chonghaejin Marine, Kim Han-sik, was arrested and faced charges including causing death by negligence. Four other company officials were also taken into custody.

The Ministry of Oceans and Fisheries cancelled Chonghaejin Marine's license to operate ferries on the Incheon-Jeju Island route in May 2014.

Owners

Yoo Byung-eun, former chairman of Chonghaejin Marine, ignored Incheon District Prosecutors' Office summonses, and went into hiding. On 22 May, the Incheon District Court issued an arrest warrant and Korean authorities offered a ₩50 million (US$48,800) reward for information leading to the arrest of Yoo. On 25 May, the reward was raised tenfold to ₩500 million (US$488,000). On 21 July 2014, it was reported that a body found in a field in June was believed to be Yoo's.

Regulation

The disaster raised questions regarding governmental regulation of shipping in South Korea. Shipping is regulated by the Korean Shipping Association, which is also an industry trade group, which experts consider a likely conflict of interest. In addition, government regulators outside the Association frequently move to jobs as part of the association after their government service. Yun Jong-hwui, a professor at Korea Maritime and Ocean University, notes that while South Korean regulations are strong, they are often poorly enforced.

Legal cases

On 3 June, the Gwangju District Court issued arrest warrants for a senior vessel safety operator of the Korea Shipping Association's Incheon unit and a vessel inspector of the Korean Register of Shipping's Mokpo unit. Amongst 15 crew accused of the sinking, prosecutors sought the death penalty for the captain under the charge of homicide and the prosecution told the court that he failed to carry out his duty. Lead prosecutor Park Jae-eok said: "Lee supplied the cause of the sinking of the Sewol...he has the heaviest responsibility for the accident. We ask that the court sentence him to death." While no formal pleas were made, Lee denied intent to kill. The others had lesser charges, including negligence. A three-judge panel would announce its verdicts in November. The Incheon District Court, on Wednesday, 5 November, sentenced the late ferry owner Yoo Byung-eun’s eldest son Yoo Dae-kyoon to three years in prison for embezzlement and breach of trust.

On 11 November 2014, the Gwangju District Court found Captain Lee Jun-seok guilty of negligence and he was sentenced to 36 years' imprisonment. The judges said that he was clearly not the only person responsible for the tragedy and they accepted that his negligence did not amount to an intent to kill. The chief engineer of the ferry, identified by his surname Park, was found guilty of murder and jailed for 30 years. Thirteen other crew members were given jail sentences of up to 20 years on charges including abandonment and violating maritime law. Relatives of victims were distraught at the verdict, with some weeping. The AFP news agency reported that one woman screamed in the courtroom: "It's not fair. What about the lives of our children? They (the defendants) deserve worse than death."

In the cases against officials over the overloading of cargo, Kim Han-sik, Chonghaejin Marine's chief executive, was found guilty of negligence and received a ten-year prison term. Six other company employees and a Korean Shipping Association official also received prison sentences.

Following appeals by prosecutors and the accused, on 28 April 2015 Captain Lee was found guilty of murder and his sentence increased to life imprisonment, while those for 14 other crew members were reduced to a maximum of 12 years, including 10 years for chief engineer Park, whose murder conviction was overturned. Judge Jeon Il-ho explained: "We drew a distinction between the Captain Lee Joon-seok who has a grave responsibility and crew members who took orders from the captain." Kim Han-sik's sentence was also reduced to seven years on appeal.

Political

In addition to reaction against the actions of the captain and much of the crew of Sewol, there has been a much wider political reaction to the disaster. Criticism has ranged from anger at the lax regulatory environment which may have contributed to the safety violations that could have sunk Sewol, to anger about the rescue operations, to anger at Park Geun-hye, the President of South Korea, whose approval ratings fell from a high of 71 percent before the disaster to "the 40 percent range" weeks afterwards.

Political reaction to the Sewol sinking has been intensified by a series of events. A prominent South Korean politician from the ruling Saenuri Party, Chung Mong-joon, was forced to apologize when his son wrote a controversial Facebook post criticizing the public for criticizing the government over the disaster. Many parents of the victims of the tragedy have been expressing deep anger at the government, ranging from reportedly berating Prime Minister Jung Hong-won to shouting at President Park Geun-hye, to parents staging protests at the presidential palace itself, partly inflamed by a reported remark by a senior news editor at the government-influenced Korean Broadcasting System that the number of dead in the ferry tragedy was "not many, compared with the number of people killed in traffic accidents each year".

Barack Obama, the President of the United States, sent his condolences, stated that the United States would help in the search for survivors, and during a state visit to South Korea presented a magnolia tree from the White House to the high school. Japanese Prime Minister Shinzo Abe offered sympathy to the victims. Truong Tan Sang, the President of Vietnam, as well as the deputy prime minister and the minister of foreign affairs, sent their condolences to Yun Byung-se, South Korea's Minister of Foreign Affairs. Singapore's Prime Minister Lee Hsien Loong sent their condolences to the president of South Korea. Xi Jinping, the President of China, sent messages on condolences to Park.

On 27 April, Jung Hong-won, the prime minister of South Korea, accepted responsibility and announced his resignation.

On 29 April, South Korean president Park Geun-hye indirectly apologized for the government's response to the ferry sinking.

On 30 April, North Korea sent its condolences.

On 18 May 2014, the BBC reported that President Park Geun-hye announced South Korea "plans to break up its coastguard" after it had failed to respond well during the MV Sewol ferry disaster. According to Park, "investigation and information roles will be transferred to the Korean police while the rescue and salvage operation and ocean security roles will be transferred to the Department for National Safety which will be newly established".

On 19 November 2014, the Korea Coast Guard ceased control as the Ministry of Public Safety and Security was founded on the same day.

Civilian

On 17 April, a representative of the Cheonghaejin Marine Company apologized for the incident. The chairman and CEO of Korean Register of Shipping, Chon Young-Kee, resigned on 28 April, following raids on KR offices by South Korean prosecutors.

On 18 April, the rescued vice principal of Danwon High School, Kang Min-kyu, 52, committed suicide by hanging himself. Police stated that a note was found in his wallet. Kang had organized the field trip that had brought the high school party aboard the ship, and had written in his two-page note that "Surviving alone is too painful when 200 lives are unaccounted for ... I take full responsibility." The note ended with a request that his body be cremated and the ashes scattered over the site of the accident, "that I might be a teacher in heaven to those kids whose bodies have not been found."

On 22 April, a netizen made a post encouraging others to take part in the 'KakaoTalk yellow ribbon wearing campaign.' The image accompanying the post had a caption stating, 'One small movement, big miracles'. Since then, the yellow ribbon has gained meaning to symbolize mourning. The ribbons are prominent in social media, sometimes as profile photos. Celebrities such as Jo Kwon and Hye-rim Park have joined the movement.

The disaster is the subject of the 2014 documentary film Daibingbel; The Truth Shall Not Sink with Sewol. The director's cut of the film was made available for public viewing on YouTube on 31 August 2015.

On 17 April 2015, a day after the first anniversary of the sinking that killed 304 people, 4,475 participants holding electronic candles formed the shape of the Sewol ferry at the commemoration event titled ‘The Saddest Challenge in the World’ in Seoul Plaza in front of City Hall. They were attempting a Guinness World Record for largest torchlight vigil image. The recent world record, called ‘Lights in the dark’, in which 3,777 participants gathered at a square in Jakarta, Indonesia as a symbol of hope and prayer, was broken by ‘The Saddest Challenge in the World’.

Government's public opinion manipulation

On 16 November 2016, the report about the MV Sewol incident for the President Park Geun-hye was revealed. This report was written by National Intelligence Service.

The NIS report called the MV Sewol incident "just a ferry accident (여객선 사고)" and said "we must control the protest in the name of ferry accident (여객선 사고를 빌미로 한 투쟁을 제어해야 한다)". In the report, there is no mention about demanding the truth, salvaging the hull, or supporting the victims' families. The report talks about only a "control the protesting attempt by the opposition forces in the name of ferry accident"s and suggest a method about public opinion manipulation using the government-organized demonstrations.

During the investigation of the 2016 South Korean political scandal on 11 January 2017, the blacklisting of Park Geun-hye Governments has including about the MV Sewol incident.