Blue Hole (Lighthouse Reef): The Blue Hole originates from a collapsed cavern, after an ice age 15,000 years ago, forming a sinkhole. Jacques Cousteau made it famous during his 1970 expedition with the Calypso. The Blue Hole is perfectly circular, and the diameter measures 1,045 feet (320 meters) and the maximum depth is 412 feet (125 meters). Except for two narrow passages on the eastern and the northern rims, the Blue Hole is completely rimmed by living coral. Most interesting about the dive is the impressive descend, and the rock formation and the stalactites. Marine live is less interesting, although you will encounter moray eels. Sharks and turtles may be found but their presence is unpredictable. This dive is a must for every self respecting diver.