- Mermaid Reef, the northeastern one of the three reefs at 17°06′S 119°37′E, is an atoll with a large lagoon enclosed by a rim of coral, which falls dry. There are many drying patches in the lagoon. On the northeast side of the reef, there is a passage, about 60 m wide, leading into the lagoon. Mermaid Reef rises steeply from the surrounding ocean floor, which is 440 m deep. The atoll was named in 1818 by Captain Philip Parker King, who discovered the reef and named it after his ship.
- Clerke Reef (also called Minstrel Shoal), at 17°19′S 119°21′E, lies about 23 km southwest of Mermaid Reef. The reef has a length of about 15 km north-south, and a width of about 6 km. Near the northern end of the reef lies Bedwell Islet, a bare sand cay about 2 m high. On the eastern and western sides of the reef there are a number of boulders which fall dry. A narrow passage leads to a lagoon, with many detached coral patches within the reef. Clerke Reef rises steeply from the surrounding ocean floor, which is 390 m deep. It was also named by Captain Philip Parker King, after Captain Clerke, who had reported it from a whaler between 1800 and 1809.
- Imperieuse Reef, at 17°35′S 118°55′E, lies about 35 km southwest of Clerke Reef and is the southwesternmost of Rowley Shoals. It is about 16 km in length north-south and has a width of about 8 km. On the southeastern edge of the reef there are numerous coral boulders, which rise about 3 m above the water mark. Large areas of the reef fall dry at low water and there are two lagoons, which each contain many coral patches within. Cunningham Islet, a small sand cay 3.7 m high and devoid of vegetation, is located close within the northern extremity of the reef, and is surrounded by a small lagoon, 93 m wide. The islet is the location of a lighthouse, Imperieuse Reef Light. Imperieuse Reef rises steeply from the surrounding ocean floor, which is 230 m deep. The reef was named by Captain Phillip Parker King after the ship (HMS Imperieuse) from which it was sighted by Captain Rowley in 1800.
Clerke and Imperieuse Reefs form the Rowley Shoals Marine Park, declared in 1990 and extended in 2004. The park is managed by the Department of Conservation and Land Management (CALM) now known as the Department of Environment and Conservation (DEC) of Western Australia.
Commonwealth marine park
Mermaid Reef Marine National Nature Reserve (Mermaid) was declared on 21 March 1991 to protect its marine life and coral formations. Mermaid is assigned the IUCN category Ia – Strict Nature Reserve, which means that it is a protected area managed mainly for scientific research or environmental monitoring. The Director of National Parks is responsible for managing all Commonwealth reserves including marine protected areas as specified by the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Mermaid Reef is listed on Australia’s Commonwealth Heritage List and all three reefs of the Rowley Shoals were registered on the former Register of the National Estate.
It is managed by the Director of National Parks  and the staff of Parks Australia (formerly the Australian Nature Conservation Agency (ANCA)) with the assistance of the WA Department of Environment and Conservation (DEC). A number of other agencies also assist in the management of Mermaid, including the Australian Customs and Border Protection Service and the Royal Australian Navy.
Interim management arrangements under the EPBC Act for Mermaid commenced on 17 May 2007 following the expiry of the first management plan. These interim management arrangements are consistent with the first management plan for Mermaid. Under the interim management arrangements, visitors to Mermaid require authorisation from the Director of National Parks to conduct certain activities. These arrangements will remain in place until a new management plan is finalised at the conclusion of the marine bioregional planning process for the north-west marine region.
The EPBC Act prohibits certain activities from being done in a Commonwealth reserve except in accordance with the management plan for the reserve. These include activities that affect native species, commercial activities and mining operations.
A range of activities in Commonwealth reserves are also controlled, or able to be controlled by the Director, under the Environment Protection and Biodiversity Conservation Regulations 2000 (EPBC Regulations), including the use of vessels, commercial activities, commercial fishing, recreational fishing and scientific research. Many of these activities are prohibited unless certain exemptions apply, including where the Director has issued a permit authorising the activity, or where a management plan in force for a reserve allows the activity.