The Rocas Atoll (Portuguese: Atol das Rocas) is an atoll in the Atlantic Ocean, belonging to the Brazilian State of Rio Grande do Norte. It is located approximately 260 km (160 mi) northeast of Natal and 145 km (90 mi) west of the archipelago of Fernando de Noronha. The atoll is of volcanic origin and coralline formation.
The oval atoll is 3.7 kilometres (2.3 mi) long and 2.5 kilometres (1.6 mi) wide. The lagoon is up to 6 metres (20 ft) deep and has an area of 7.1 square kilometres (2.7 sq mi). The land area of the two islets (Cemitério Island, southwest and Farol Cay, northwest) is 0.36 square kilometres (89 acres). Farol Cay accounts for almost two thirds of the aggregate area. The highest point is a sand dune in the south of larger Farol Cay, with a height of 6 metres (20 ft). Both islets are overgrown with grasses, bushes and a few palm trees. There are crabs, spiders, scorpions, sand fleas, beetles, large roaches, and many species of birds.
There is a lighthouse of the Brazilian Navy that has been in operation and maintained since the 1960s, at the Northern end of Farol Bay. In its vicinity is a derelict lighthouse from 1933.
The atoll is a wildlife sanctuary, and in 2001 was designated by UNESCO as a World Heritage Site. Numerous turtles, sharks, dolphins and birds live in the area. The atoll consists mainly of coral and red algae. The coral ring is almost closed, with a 200 metres (660 ft) wide channel on the North side and a much narrower channel on the West side.
A biological reserve, it is currently used solely for scientific research. Due to their remote location, the islands remain largely undisturbed by the human activities. On the other hand, it also limits researchers access to the islands and few studies have been developed in this atoll. The entomological fauna from Atol das Rocas was already recorded.