Commodore Reef, also known as Rizal Reef, is a atoll located in the southeast of Dangerous Ground in the Spratly Islands in the South China Sea. It is located east of the Ardasier Reef and Investigator Shoal, 117.9 miles (189.7 km) NE of Swallow Reef and 167.1 miles (268.9 km) SE of Cuarteron Reef. The rock has been legally declared a rock.

The Spratly Islands are a disputed archipelago in the South China Sea. Composed of islands, islets, cays, and more than 100 reefs, sometimes grouped in submerged old atolls, the archipelago lies off the coasts of the Philippines, Malaysia, and southern Vietnam. Named after the 19th-century British whaling captain Richard Spratly who sighted Spratly Island in 1843, the islands contain less than 2 km2 of naturally occurring land area, which is spread over an area of more than 425,000 km2 (164,000 sq mi).