Blue Hole on Long Island, Bahamas
This is touted to be the deepest blue hole in the world at 600+'. It's unusual, not only because of it's depth, but you can wade out from the beach in knee deep water to it's edge and then...WOW!
There are international freediving championship meets held here every year. It's interesting to watch these young men and women from all over the world (without an ounce of body fat) compete.
We watched a young fellow with one fin attached to both feet (think mermaid tail) free dive to almost 400'! Most impressive.