Beneath the land surface of the Bahamas, the underwater caves known as blue holes stretch for hundreds of miles in all directions. Today, these labyrinthine passages host a variety of tiny sea ...

Like a giant bathtub drain ... Dean’s Blue Hole—Earth’s deepest known underwater cave—plunges more than 600 feet into darkness. The entry to South Passage is decorated by spectacular ...

But there is hope, says Thymann, and documenting this dense habitat of underwater caves may be the first step in protecting the manatees that live there. Receive a weekly dose of discovery in your ...