Worlds Largest Natural Formation, The Great Blue Hole

The hole is spherical in shape, over 300 meters (984 ft.) across and 125 meters (410 ft.) deep. It is the world's largest natural formation of its kind, the Great Blue Hole is part of the larger Barrier Reef Reserve System, a World Heritage Site of the United Nations Educational, Scientific and Cultural Organization (UNESCO). Glyn Collinson, a NASA scientist who recently dived the Great Blue Hole described it as, "It was the deepest, deep blue hole imaginable; A chasm that fell away deep into the deep, dark blue. It had been forged out of solid rock as caverns, hundreds of thousands of years ago during the last ice age. For eons, water filtered through the rock and into these great stone cathedrals, breeding multicolored stalactites and stalagmites. Then, one by one they collapsed in on each other, creating a chasm four hundred feet deep. As Earth's swollen polar ice-caps receded, the warm Caribbean ocean swept in to fill the chasm with boiling white hands, the last rays of sunlight struck the chasm's floor. Then, as the limestone broke down, it began to rain tiny fragments of rock, which slowly began to fill the great Blue Hole."