For people with "thalassophobia," or the fear of deep bodies of water, blue holes are something out of a nightmare. These massive vertical caves open up in the shallow waters near coastlines, but blue ...

There’s an underwater sinkhole off the coast of Belize that is so deep, scientists aren’t sure how far down it goes. In Chetumal Bay, sinkhole Taam ja’, a ‘blue hole’, has proved to be a challenge for ...