Union Banks

Union Banks is a large drowned atoll in the center of Spratly Islands in South China Sea, 230 kilometers west of the Philippine coast, containing islands and reefs whose ownership remains disputed and controversial. The closest atoll is Tizard Bank, 25 kilometers due north of Union Banks. There are only two natural islands on the rim of the reef, Sin Cowe Island and Sin Cowe East Island.

The atoll is 55 kilometers long from Johnson South Reef in the southwest to Whitson Reef in the northeast, and up to 15 kilometers wide. Its total area measures 461 km². The central lagoon is up to 53 meters deep.