The 51st parallel south is a circle of latitude that is 51 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, the Indian Ocean, the Pacific Ocean and South America.
At this latitude the sun is visible for 16 hours, 33 minutes during the December solstice and 7 hours, 55 minutes during the June solstice.
51st parallel south Wikipedia
Starting at the Prime Meridian and heading eastwards, the parallel 51° south passes through: