From the deep ocean floor to vast underground caverns beneath our feet, these places challenge our understanding of the world.

This 2020 astronaut photo shows the unusual cetacean-like shape of Belize's Lighthouse Reef. It's home to the famous Great ...

The bold question-askers at What If explore what happens if you fell into the deepest hole on Earth. I Sat Next To A Gun ...

Dubbed the 'Great Blue Hole' of Belize, it is one of the deepest sinkholes on the planet. At about 300 feet deep, the hole ...

Imagine diving into a hole so deep, it seems to have no bottom — that's exactly what scientists just found off the coast of Mexico. This newly discovered blue hole is even deeper than expected, and ...