This extraordinary image captures the meeting place of the deep waters of the Tongue of the Ocean and the much shallower, completely submerged Grand Bahama Bank. This platform reef drops off quickly into a branch of the Great Bahama submarine canyon. Because of its shape, this branch is called the Tongue of the Ocean. The vertical rock walls of the canyon rise 14,060 feet from their greatest depth to the surrounding seabed, which is why the water here appears darker in color than the water found over the adjacent reef. The shallowest parts of the reef are no more than three to seven feet deep—so shallow, in fact, that in the northeast corner of the image you can see large wave-sized ripples of sand on the seafloor. Like many other biological structures, the ribbon-like shape of the reef maximizes surface area and thus the number of organisms that can colonize the structure. The nearest island is Great Exuma, which is located about 16 miles to the east.