The Great Blue Hole of Belize looks like a large submarine sinkhole off the coast of Belize, It lies near the center of Lighthouse Reef, a small atoll 70 km (43 miles) from the mainland and Belize City. In reality, the 1,000-foot (305 meter) wide hole is simply a sinkhole in the ocean. Geologists consider that an underlying cave system collapsed under increased pressure some 10, 000 years in the past as a result of rising sea levels.
The blue hole descends 412 feet (126 meters), terminating in the lightless depths in which insufficient supply of oxygen avoids most various types of life from growing. Divers do not usually dive with these types of depths, but, as many are content to discover the stalactite-rich caverns reachable from depths of certain 130 feet (40 meters) below the surface area.