<Tr> <Th> Pop . density </Th> <Td> 438.74 / km (1,136.33 / sq mi) </Td> </Tr> <Tr> <Th> Ethnic groups </Th> <Td> White 80.5%, Mulatto 10.9%, Black 8.0%, Amerindian 0.4%, Asian 0.2% </Td> </Tr> <P> The geography of Puerto Rico consists of an archipelago located between the Caribbean Sea and the North Atlantic Ocean, east of the Dominican Republic and west of the Virgin Islands . The main island of Puerto Rico is the smallest and most eastern of the Greater Antilles . With an area of 3,515 square miles (9,104 km), it is the third largest island in the United States and the 82nd largest island in the world . Various smaller islands and cays, including Vieques, Culebra, Mona, Desecheo, and Caja de Muertos comprise the remainder of the archipelago with only Culebra and Vieques being inhabited year - round . Mona is uninhabited through large parts of the year except for employees of the Puerto Rico Department of Natural Resources . </P> <P> The mainland measures some 96 nautical miles (110.5 mi; 177.8 km) by 35 nautical miles (40.3 mi; 64.8 km), an area slightly less than three times the size of the U.S. state of Rhode Island . It is mostly mountainous with large coastal areas in the north and south regions of the island . Some popular beaches on the north - west side of the island are Jobos Beach, Maria's Beach, Domes Beach and Sandy Beach . The main mountainous range is called La Cordillera Central (The Central Range). The highest elevation point of Puerto Rico, Cerro de Punta (4,390 feet or 1,338 meters), is located in this range . Another important peak is El Yunque, located in the Sierra de Luquillo at the El Yunque National Forest, with a maximum elevation of 3,494 feet (1,065 m). The capital, San Juan, is located on the main island's north coast . </P>

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