This astronaut photograph highlights the coral reef atolls known as Rowley Shoals, located in the southwestern Timor Sea. Three reef areas make up the shoals—Mermaid Reef, Clerke Reef, and Imperieuse Reef—which extend approximately 100 kilometers (62 miles) from northeast to southwest. Only Clerke Reef and Imperieuse Reef have white sandy islets (or cays) that remain above water. Imperieuse Reef also has the only permanent man-made structure: a lighthouse on Cunningham Islet, a cay at the northern end of the reef.
Rowley Shoals is located off the northwestern Australia coastline, approximately 300 kilometers (185 miles) west of the city of Broome. Since the late 1970s, fishing and diving expeditions have frequented the atolls. Clerke and Imperieuse Reefs are part of the Rowley Shoals Marine Park, established in 1990. Mermaid Reef is managed as the Mermaid Reef Marine National Nature Reserve, established in 1991.
The biodiversity of the atolls is impressive, with 233 coral species and 688 fish species more typical of Southeast Asia than other Western Australian reef ecosystems. Species include staghorn coral, giant clams, giant potato cod, maori wrasse, mackerel, and tuna. In addition, Bedwell Island (a cay in Clerke Reef) hosts a colony of red-tailed tropicbirds, as well as species of shearwaters, sea eagles, terns, plovers, and egrets.