Union Banks is a large drowned atoll in the center of Dangerous Ground in the Spratly Islands in South China Sea, 230 kilometres (120 nautical miles) west of the Philippine coast, containing islands and reefs whose ownership remains disputed and controversial. The closest atoll is Tizard Bank, 25 kilometres (13 nautical miles) 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 kilometres (34 miles) long from Johnson South Reef in the southwest to Whitson Reef in the northeast, and up to 15 kilometres (9.3 miles) wide. Its total area measures 461 square kilometres (178 square miles). The central lagoon is up to 53 metres (174 feet) deep.
Key: yellow = occupied by PRC; violet = occupied by Vietnam
|Johnson South Reef (Chigua Jiao)|
|Collins Reef (Đá Cô Lin)|
|Đá Tam Trung|
|Sin Cowe Island (Sinh Tồn)|
|Hughes Reef (Dōngmén jiāo)|
|Sin Cowe East (Sinh Tồn Đông)|
|Bamford Reef (Đá Vị Khê)|
|Lansdowne Reef (Đá Len Đao)|
This list includes the names of all Spratly features known to be occupied and/or above water at low tide.