English: This satellite image of Grand Bahama has been cropped from an image of Florida, Cuba, and the Bahamas.

"Underwater features are actually more striking than surface features in this Moderate Resolution Imaging Spectroradiometer (MODIS) image, acquired on January 24, 2004, by NASA’s Terra satellite. The Great Bahama Bank and Little Bahama Bank are a brilliant blue in contrast to the black of the surrounding ocean. The Banks are shallow coral reefs that reflect light through the ocean, giving it a bright blue color. The ocean becomes suddenly deep on the western edge of the Grand Bahama Bank, and here it becomes an inky black. Coral reefs are also visible around the Florida Keys and in the Golfo de Batabanóuth of Cuba. Near land, sediment may also be coloring the water. Like coral reefs, sediment reflects light through the water, giving it a bright color. A few fires were burning when this image was acquired, and they have been marked with red dots."

Description at NASA's Visible Earth website