From the NASA Earth Observatory Image of the Day: The Tuamotu Archipelago is part of French Polynesia, and forms the largest chain of atolls in the world. This astronaut photograph features Mataiva Atoll, the westernmost atoll of the Tuamotu chain. Mataiva Atoll is notable in that its central lagoon includes a network of ridges (white, image center) and small basins formed from eroded coral reefs. Mataiva means “nine eyes” in Tuamotuan, an allusion to nine narrow channels on the south-central portion of the island. The atoll is sparsely populated, with only a single village—Pahua—located on either side of the only pass providing constant connection between the shallow (light blue) water of the lagoon and the deeper (dark blue) adjacent Pacific Ocean. Much of the 10-kilometer- (6-mile-) long atoll is covered with forest (greenish brown). Vanilla and copra (dried coconut) are major exports from the atoll, but tourism is becoming a larger part of the economy.
This is not a satellite image, but a photograph taken by the Expedition 24 crew from the International Space Station (I think) on August 13, 2010, with a Nikon D2Xs digital camera using a 400 mm lens. More here.