Rio Grande do Norte (lit. "Great Northern River", in reference to the mouth of the Potenji River, ) is one of the states of Brazil, located in the northeastern region of the country, occupying the northeasternmost tip of the South American continent. Because of its geographic position, Rio Grande do Norte has a strategic importance. The capital and largest city is Natal. It is the land of the folklorist Luís da Câmara Cascudo and, according to NASA, it has the purest air in the Americas. Its 410 km (254 mi) of sand, much sun, coconut palms and lagoons are responsible for the fame of beaches. Rocas Atoll, the only such feature in the Atlantic Ocean, is part of the state. The main economic activity is tourism, followed by the extraction of petroleum (the second largest producer in the country), agriculture, fruit growing and extraction of minerals, including considerable production of seasalt, among other economic activities. The state is famous for having many popular attractions such as the Maior cajueiro do mundo (world's largest cashew tree), the dunes and the dromedaries of Genipabu, the famous beaches of Ponta Negra, Maracajaú and Pipa's paradise, the Carnatal the largest off-season carnival in Brazil, the Forte dos Reis Magos is a sixteenth-century fortress, the hills and mountains of Martins, the Dunas Park the second largest urban park in the country, and several other attractions. The state is also closest to the archipelago of Fernando de Noronha.