They were rolling in the deep. Scientists have identified what could potentially be the “deepest known blue hole” in the world, extending so far down that the bottom has not yet been reached.

Plunge into this deep blue hole and you'll discover imposing ancient stalactites (calcium deposits resembling icicles) and coral fringe. Declared a UNESCO World Heritage Site in 1996 – along ...

A water-filled natural limestone cavern, Dean's Blue Hole plunges 663 feet below ground level on Long Island, part of a string of Bahamian islands south of Nassau and New Providence Island.