13.Great Blue Hole

We can understand if you think the image is photoshopped. How can a sinkhole be that perfectly round? Well, the Great Blue Hole off the coast of Belize is in fact very round at the surface, and was made famous by renowned explorer and conservationist Jacques Cousteau. The hole was originally formed by glaciers starting some 153,000 years ago, when sea levels were much lower. The sinkhole continued to be altered as little as 15,000 years ago. The Great Blue Hole is part of the Belize Barrier Reef Reserve System, a UNESCO World Heritage Site.

While only experienced divers should dare venture into the Great Blue Hole, the next sinkhole is perfect for the whole family.