Great Blue Hole
This is the Great Blue Hole off the coast of Belize. It is a giant marine sinkhole 1,043 feet across (317 meters) with a depth of 407 feet (124 meters). A marine sinkhole is a cave flooded by rising water, often after quaternary glaciation. Recreational scuba is common in the hole. Discovery Channel placed it number one on “The 10 Most Amazing Places on Earth.”