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13 amazing sinkholes

By: Laura Moss on Oct. 6, 2010, 11:22 a.m.
The Great Blue Hole in Belize

Photo: Wikimedia Commons

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The Great Blue Hole

The Great Blue Hole is a large underwater sinkhole off the coast of Belize that’s more than 1,000 feet wide and 400 feet deep. It formed as a limestone cave system during the last ice age when sea levels were lower, and the caves flooded as the planet warmed and sea levels rose.

Jacques-Yves Cousteau made the site famous in 1971 when he declared it one of the top 10 scuba diving sites in the world, and today it is a World Heritage Site.