LOCATION, SIZE, AND EXTENT
Situated on the ne periphery of the Caribbean Sea, about 1,000 mi (1,600 km) se of Miami, Puerto Rico is the easternmost and smallest island of the Greater Antilles group. Its total area is 3,515 sq mi (9,104 sq km), including 3,459 sq mi (8,959 sq km) of land and 56 sq mi (145 sq km) of inland water.
Shaped roughly like a rectangle, the main island measures 111 mi (179 km) e-w and 36 (58 km) n-s. Offshore and to the e are two major islands, Vieques and Culebra.
Puerto Rico is bounded by the Atlantic Ocean to the n, the Virgin Passage and Vieques Sound to the e, the Caribbean Sea to the s, and the Mona Passage to the w. Puerto Rico's total boundary length is 378 mi (608 km).
About 75% of Puerto Rico's land area consists of hills or mountains too steep for intensive commercial cultivation. The Cordillera Central range, separating the northern coast from the semiarid south, has the island's highest peak, Cerro de Punta (4,389 ft-1,338 m). Puerto Rico's best-known peak, El Yunque (3,496 ft-1,066 m), stands to the east, in the Luquillo Mountains (Sierra de Luquillo). The north coast consists of a level strip about 100 mi (160 km) long and 5 mi (8 km) wide. Principal valleys are located along the east coast, from Fajardo to Cape Mala Pascua, and around Caguas, in the east-central region. Offthe eastern shore are two small islands: Vieques, with an area of 51 sq mi (132 sq km), and Culebra, covering 24 sq mi (62 sq km). Uninhabited Mona Island (19 sq mi-49 sq km), off the southwest coast, is a breeding ground for wildlife.
Puerto Rico has 50 waterways large enough to be classified as rivers, but none is navigable by large vessels. The longest river is the Rio de la Plata, extending 46 mi (74 km) from Cayey to Dorado, where it empties into the Atlantic. There are few natural lakes but numerous artificial ones, of which Dos Bocas, south of Arecibo, is one of the most beautiful. Phosphorescent Bay, whose luminescent organisms glow in the night, is a tourist attraction on the south coast.
Like many other Caribbean islands, Puerto Rico is the crest of an extinct submarine volcano. About 45 mi (72 km) north of the island lies the Puerto Rico Trench, at over 28,000 feet (8,500 meters) one of the world's deepest chasms.
Tradewinds from the northeast keep Puerto Rico's climate equable, although tropical. San Juan has a normal daily mean temperature of 80°f (27°c), ranging from 77°f (25°c) in January to 82°f (28°c) in July; the normal daily minimum is 73°f (23°c), the maximum 86°f (30°c). The lowest temperature ever recorded on the island is 39°f (4°c), at Aibonito, the highest 103°f (39°c), at San Lorenzo. The recorded temperature in San Juan has never been lower than 60°f (16°c) or higher than 97°f (37°c).