Hundreds of feet below the surface of the Caribbean Sea, a submarine glides through one of the most mysterious places on Earth. This is the Great Blue Hole, a 1,000-foot-wide abyss formed thousands of years ago in the middle of the ocean. And now a band of explorers is finally plumbing its vast depths – but what they find has scary implications for the future of mankind.
In Central America, between Mexico and Guatemala, sits the tropical country of Belize. The Mayans, an advanced civilization that built many monuments and cities across the region, actually thrived there until around 1200 A.D. But when European explorers arrived in the early 16th century, they changed the face of the country forever.