Belize

There is a natural phenomenon called Blue Hole (Blue Hole), which are nothing more than vertical or sinks underwater caves. Are nearly circular, steep-walled and so named because the dramatic contrast between the dark blue of the deep water and the clearest of shallow around. Were formed during the Ice Age, about 15,000 years ago and although the depths are variable, usually about 100 m.

However, Dean's Blue Hole shows exceptional features: with a depth of 202 meters is the deepest in the world. It is located in the Bahamas, near the center of Lighthouse Reef, 100 kilometers from the mainland coast of Belize.
 
It is very circular surface with a diameter of about 25 to 35 meters. At a depth of 20 meters the hole widens considerably into a cavern that has formed about 100 meters in diameter.

Guillaume Nery, athlete specializing in free diving, descended into this hole and breaking the world record for the record in a spectacular video images.