Serranilla Bank is an atoll in the southeastern Carribean. It is approximately 400 kilometres (250 mi) northeast of Nicaragua. Only the eastern and southern part of the reef are visible. The bank is made of several cays, and has a size of about 45 kilometres (28 mi) by 37 kilometres (23 mi). It covers an area of about 1,200 square kilometres (460 sq mi).Many parts of the coral reef are dry at low tide. The ocean has a depth of between 9 metres (30 ft) and 37 metres (121 ft) in most parts.
Northeast Breaker is a rock formation located about 2 kilometres (1.2 mi) from the eastern rim.
East Cay is a small island, about 5.5 kilometres (3.4 mi) wast of the eastern rim. It is covered with bushes.
Beacon Cay is the biggest island of trhe bank. It is about 14 kilometres (8.7 mi) southwest of East Cay. It is a sandy island, with some coral rock formations. It is coverted with bushes. Grass grows in some places. Between 30 and 50 coconut palms grow of the island. There is a daymark made of corals at the western end. There are some buildings. There's also an active lighthouse which has been in use since 1977. It is made of steel. The lighthouse is probably operated by Colombian authorities.
Middle Cay is a small island, made of sand. It is about 3.5 kilometres (2.2 mi) west of East Cay.
West Beaker is a rock formation about 15 kilometres (9.3 mi) west of Beacon Cay. The rock formation is dangerous for ships, because it is only about 0.5 metres (1 ft 8 in) above the water surface, on a platform, made of corals. Sailors mentioned in 1985, that the maps of the time were inaccurate, and that the rocks extend another 3.5 kilometres (2.2 mi) westward.