The Huffpo has a video of world champion freediver Guillaume Nery diving underwater into Dean's Blue Hole.
Dean's Blue Hole is the world's largest underwater sinkhole, plunging 663 feet to the ocean floor in a bay west of the Bahamas. Nery says he never reached the bottom; the distance is so far as to make it impossible. Nery says, "This movie is an artistic project, a fiction." He shot it with his girlfriend over the course of four afternoons:
It may be a fiction but it's nevertheless quite beautiful.
RLC