Coral Island, North Natuna Archipelago, Indonesia
25 October 2012

Note: The area of coverage in this WorldView-2 image is 4.5 km x 4.5 km.
The reduced resolution image on display has undergone compression and so does not represent the true resolution of the original satellite image.

Two isolated coral reefs, looking like giant footprints, occur off the north coast of Natuna Besar Island, South China Sea. The western part of the larger reef emerges above water to form an elliptical island, well vegetated, and flanked by a narrow sandy beach. A tombolo attaches this island to a number of very small ones towards the west, which are higher parts of the reef complex. Variations in reflectance indicate existence of the reef at different depths under water while the edges drop off steeply to the sea floor. The upper surface of the smaller of the two reefs, the other footprint, is nearly at sea level. Waves break over the higher parts of its edge. A fringing reef has also developed along the coast of Natuna Besar. Sediment waves are visible under water, travelling in the channel between the main island and the reefs.