A group of friends, Amy (Susan May Pratt), James (Richard Speight, Jr.), Zach (Niklaus Lange), Lauren (Ali Hillis), Dan (Eric Dane), and Dan's new girlfriend Michelle (Cameron Richardson) go for a weekend cruise on Dan's new yacht. Amy and James also bring their infant daughter, Sarah.
Most of the friends decide to jump into the water for a swim. Amy, who is hydrophobic after a childhood incident, refuses but Dan picks her up and dives in with her. However, nobody thought to lower the ladder to re-board the ship, and so everyone (except the baby) is trapped in the water with only two masks, a dive knife, and a toy dolphin float. Despite their efforts, the side of the yacht is too smooth to climb and the deck is too high to reach. They see a boat of teenagers heading towards them. The group try to grab their attention, but the teenagers think that they are just greeting them, and sail off. During the struggle, the group try using a phone to call for help, only to hear the voices of some well wishers, unable to get the caller's attention. The phone accidentally gets knocked in the water.
They are left to tread water disconsolately. The group resorts to removing and using their bathing suits to make a rope. After a couple of attempts they manage to get one end of the rope wrapped around a railing. Instead of having the lightest person climb up, Zach attempts to climb. He pulls himself up and his fingers brush the gunwale but the makeshift rope rips apart as he is too heavy. The group are now mostly naked and have only a partial rope.
Meanwhile, James goes underwater, and is fooling around with the prop, in an attempt to remove it and use it as a grappling hook, but he drops the knife. He swims down after it and manages to catch it, and desperately tries to swim for the surface. As he swims back up he crashes into the bottom of the boat, and is knocked unconscious. He resurfaces motionlessly and slightly bloodied with an apparent skull fracture. Zach gets the knife from James and starts stabbing the boat to climb back up. Dan tries to stop Zach, but accidentally stabs him, causing Zach to drop the knife.
In a fit of hysteria and fearing that sharks will be attracted by the blood, Michelle begins to swim away, but sinks underwater. Dan swims after her and sees her lifeless body drifting underwater. He dives after her, but he can't reach her, and her body disappears into the depths. After some time, Zach dies from blood loss in Lauren's arms. She reluctantly lets go of his body which floats away, face down. After much waiting, Lauren says she refuses to die treading water and attempts to swim back to shore to find help. Her fate after this is unknown.
Later that night, during a rainstorm, James dies from his head injury. Dan unsuccessfully searches underwater for the knife. He slams his mask on the hull in frustration and the lens pops out. Remembering Zach's attempt with the knife, Dan uses it to wedge in the crevice of the side door for the ladder, giving him a handhold. Amy climbs over his shoulders, finally stepping onto his hand wrapped around the lens,causing him to yell as his hand bleeds more and manages to grab the gunwale and pull herself back on board. Once on board, she lowers the ladder for Dan and tends to her baby, Sarah. Amy notices Dan swimming away to drown out of guilt. She jumps back in to save him, reminding her when she attempted to save her father in the same manner, at a young age.
The next morning, a fishing boat approaches the yacht, and notices the lowered ladder and life ring still floating in the water - no one had pulled them in. The yacht appears empty except for the sound of Sarah crying on the lower deck.
The film cuts to Amy standing on the boat in the sun, looking around appearing heartbroken. Dan is shown lying face down on the boat with a towel covering his lower half, seemingly sleeping.Susan May Pratt as Amy
Alexandra Raach as young Amy
Eric Dane as Dan
Richard Speight Jr. as James
Niklaus Lange as Zach
Ali Hillis as Lauren
Cameron Richardson as Michelle
Wolfgang Raach as Amy's father
Open Water 2: Adrift received mixed reviews from critics. Review aggregate website Rotten Tomatoes gave the film an overall score of 40% based on 10 reviews.
In the United Kingdom, the film opened at 327 theaters, grossing £337,474, averaging £1,033 per theater. 123 theaters dropped the film for the second weekend, and its ticket sales declined by 75 percent, making £85,541, averaging £419. During the third weekend, the film's sales tumbled 90 percent after 183 more theaters dropped it, making £8,896. The fourth weekend brought an additional 64 percent decline, and the film lost 13 theaters, while grossing £3,198. In the UK, the film finished with an overall gross of £707,352.
In Germany, the film's opening weekend brought €293,601, averaging €3,764 at 78 theaters. During the second weekend in Germany, the film grossed €121,997, averaging €1,564 at 78 theaters. In Germany, the movie grossed at least €496,357.
In Spain, the film's opening weekend earned €270,396, averaging €1,767 at 153 theaters. During the second weekend, the film grossed €139,503. In Spain, the film grossed at least €713,834.
The film has grossed £2,583,205 worldwide.