The Indispensable Reefs are a chain of three large coral atolls in the Coral Sea. They are located about 50 km south of Rennell Island, separated from it by Rennel Trough. The chain stretches over a length of 114 km and its average width is 18 km.
Administratively the Indispensable Reef belongs to the Rennell and Bellona Province of the Solomon Islands.
The three atolls are steep-to and each encloses a large deep lagoon. They are separated by deep passages two to three km wide. of the Indispensable Reef are aligned in a NW-SE direction:
- North Reef is 18 km long, and up to 7 km wide. The rim of the atoll has two narrow openings in the north and northwest. The reef has a total area of 100 km², including lagoon and reef flat. There are no islets.
- Middle Reef is 51 km long. Little Nottingham Islet is a small islet located near the center of the reef. Besides its main lagoon, Middle Reef has a separate smaller northern lagoon. The total area is about 300 km².
- South Reef is 21 km long and up to 8 km wide. It encloses a lagoon 18 to 35 meters deep. The total area exceeds 100 km².
struck Indispensable Reef on August 3 1868 and was lost. The crew was rescued by the SS Boomerang.
During World War II a Japanese torpedo plane from carrier Shokaku crashed on Indispensable Reef.
In the 1980s the Solomon Islands Government apprehended a vessel from Taiwan that had been poaching the giant clam stocks of Indispensable Reef. Corals and endangered fish species are also being plundered for the aquarium trade.
- Sunken ships:
- Ecological concern: