The Lighthouse Atoll in the Belize Barrier Reef is featured in this image acquired on 29 March 2011 by Japan’s ALOS satellite. In the upper-central part of the image, an underwater sinkhole known as the Great Blue Hole appears as a dark blue circle. Also visible in the image are two coral islands – green with vegetation – called cayes. The larger to the west is Long Caye, and the smaller Half Moon Caye is to the east. See more at http://www.esa.int/spaceinimages/Images/2013/04/Belize_Barrier_Reef
