What's at the bottom of the Mariana Trench, and how do we know? How deep does the ocean go? We'll answer these questions and more in this deep dive into the world's oceans. Come on in: The water's ...

The Titanic is farther down than the deepest-diving mammal, the Cuvier's beaked whale, ventures. Even this wreck doesn't come close to the deepest-crewed mission that reached 35,839 feet in 2019. Just ...