The Great Blue Hole is a flooded sinkhole that lies 50 miles off the coast of Belize. The hole is 1,000 feet wide and about 410 feet, the bottom of which is so murky and limited in oxygen it’s claimed to be unlivable for most creatures.

The Lighthouse Reef surrounding the hole is so much lighter in color that the hole visibly stands out as seen from space.

The Blue Hole formed as a limestone cave during the last glacial period. As sea levels rose, the cave collapsed and thus created the mysterious-looking blue hole.

Undersea explorer Jacques Cousteau made the site popular when he declared it one of the top diving sites in the world in 1971. It is teeming with magnificent marine life. Hello, sharks!

A team of scientists and explorers led by Richard Branson used two submarines to help map the hole for the first time in 2018.

The Blue Hole is now part of the Belize Barrier Reef System, a 190-mile-long swath of coral that UNESCO declared a World Heritage site in 1996.