Divers once believed the Great Blue Hole was bottomless; then explorers discovered human remains deep inside

• Image: WikipediaFrom above, the Great Blue Hole is breathtaking.
• A near-perfect circle of deep blue sits in the middle of the turquoise waters of the Belize Barrier Reef, attracting divers from around the world with the promise of giant stalactites, reef sharks and one of the planet's most iconic underwater landscapes.
• Yet beneath its postcard-perfect surface lies a far more unforgiving environment.