Located on the edge of the Australian continental shelf, some 280 km west from the Western Australian town of Broome (see panoramic image), lies a trio of atoll-like reefs known as the Rowley Shoals. They rise from the edge of an undersea feature known as the Scott Reef/Rowley Shoals platform with shallower shelf waters on their eastern sides and deeper, off-shelf waters on their western sides.
The Rowley Shoals comprise three lozenge-shaped reefs — Imperieuse Reef, Clerke Reef, and Mermaid Reef — each covering around 80-90 km² in area. Each reef can be characterised by a continuous outer reef rim and a by the presence of a large central lagoon that is broken by one or more passages on the eastern side of the reef.
Both Clerke Reef and Imperieuse Reef have large permanent sand cays — Mermaid Reef has no permanent land, except at low tide when several sand banks are exposed by the receding waters.
Because of their isolation, untouched and pristine environment and rich marine life the reefs are protected: Clerke and Imperieuse Reefs form the Rowley Shoals Marine Park (which is managed by CALM), while Mermaid Reef is protected by the Mermaid Reef Marine National Nature Reserve (proclaimed in 1991), which is managed by Environment Australia.