Narrator: There's a massive underwater sinkhole off the coast of Belize that extends 125 meters into the Earth's crust. It's called the Great Blue Hole. Scuba divers and snorkelers have been ...

The Great Blue Hole is a massive marine sinkhole in the Caribbean, situated off the coast of Belize. Its diameter is 1,043 feet, and its depth reaches 407 feet.

Declared a UNESCO World Heritage Site in 1996 – along with six other areas surrounding Belize's barrier reef – the Great Blue Hole remains one of the world's most distinguished scuba sites.