outline that can be easily seen from the surface.

The Great Blue Hole of Belize

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The most famous blue hole is located off the coast of Belize, a small country on the eastern coast of Central America. It lies near the center of Lighthouse Reef, a small atoll 70 km from the mainland and Belize City. The Great Blue Hole is over 300 meters across and 124 meters deep, and was formed during several episodes of quaternary glaciation between 150,000 to 15,000 years ago. It’s a popular spot among recreational scuba divers.

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Dean's Blue Hole

Dean's Blue Hole near Clarence Town on Long Island, Bahamas, is the world's deepest known blue hole. While most blue holes and sinkholes reach a maximum depth of 110 meters, Dean's Blue Hole plunges tomore than 200 meters, which makes it quite exceptional. At the surface, Dean's Blue Hole is roughly circular, with a diameter ranging from 25 to 35 meters. After descending 20 meters, the hole widens considerably into a cavern with a diameter of 100 meters.

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Blue Hole of Dahab

This blue hole is located on the coast of the Red Sea, a few kilometers north of Dahab, Egypt. It is the second deepest blue hole at 130 meters. The Blue Hole has claimed the lives of many divers who tried to find the tunnel through the reef (known as "The Arch") connecting the Blue Hole and open water at about 52 meters depth.

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The Blue Hole of Gozo

The Blue Hole is located on the west coast