II.

Physical Geography

Puerto Rico is the easternmost island of the Greater Antilles. It is bounded by the Atlantic Ocean on the north and the Caribbean Sea on the south. Mona Passage separates Puerto Rico from the Dominican Republic (on the island of Hispaniola) to the west; the Vieques Passage separates it from its island of Vieques to the east. Puerto Rico is located 1,600 km (1,000 mi) southeast of Florida, and about 965 km (600 mi) north of Caracas, Venezuela. The Virgin Islands lie about 65 km (40 mi) to the east (see Virgin Islands of the United States; British Virgin Islands).

The total area of Puerto Rico, including its three largest offshore islands, is 13,792 sq km (5,325 sq mi). The main island is shaped like a rectangle, with a maximum length from east to west (from Punta Puerca to Punta Higuero) of 180 km (110 mi) and with a maximum width from north to south (from Isabella to Punta Colón) of 65 km (40 mi).

Hills and steep mountains cover three-fourths of Puerto Rico. A narrow coastal plain and some inland valleys provide the only low-lying terrain. The central mountain chain is the Cordillera Central, which extends east and west and divides the island into its northern and southern regions. Other mountain ranges include Sierra de Luquillo in the northeast, Sierra de Cayey in the southeast, and Sierra Bermeja in the southwest. The highest point on the island is Cerro de Punta (1,338 m/4,390 ft) in the central part of the island. The most famous peak is El Yunque (Spanish for “the Anvil”), which rises 1,066 m (3,496 ft) above sea level in the Sierra de Luquillo. El Yunque is part of the Caribbean National Forest, and it has a tropical rain forest, which is a favorite tourist attraction. The coastal plain, which rings the mountains, is about 16 km (10 mi) wide in the north and about 13 km (8 mi) wide along the southern coast.

Puerto Rico possesses several offshore islands, the largest of which are Vieques, Culebra, and Mona. Vieques, which lies to the east, is the largest (population, 2000, 9,106). Its only urban center is Isabel Segunda. North of Vieques is the smaller island of Culebra (1,868). Its main town is Dewey. The U.S. Fish and Wildlife Service protects much of the island as a natural preserve. The third island, Mona, lies to the southwest in the Mona Passage. Much smaller than Vieques or Culebra, Mona Island is uninhabited and is known for its marine life.

A.

Rivers

Puerto Rico has many relatively short rivers and streams. Some of the rivers are dammed for hydroelectric power and thus have small lakes along their courses. One such body of water is Lago de Yauco, on the Yauco River. The longest river is the Grande de Arecibo, which flows to the northern coast. Other rivers include the Grande de Añasco, Bayamón, Cibuco, Culebrinas, La Plata, and Loíza. None of the rivers is navigable by large vessels.

B.

Coastline

Puerto Rico’s coastline is well known for its beaches. It measures some 500 km (310 mi) and has few inlets, natural harbors, or protected bays. The ocean around the island is very deep; the Puerto Rico Trench, north of Puerto Rico, is 8,605 m (28,231 ft) below sea level at its greatest depth. This is the deepest known point in the Atlantic Ocean.

C.

Climate

Puerto Rico has an agreeable climate. It is tropical at the lower elevations and subtropical at the higher elevations. There is little difference from season to season, and the length of the day remains fairly constant throughout the year.

San Juan has a mean July temperature of 28°C (83°F) and a mean January temperature of 25°C (77°F). The average temperature of the seawater surrounding the island is 27°C (81°F), with little variation during the course of the year.

The entire island is cooled by the trade winds from the northeast. This air also contains much water vapor. As the air is forced to rise over the mountains, it becomes cooler and the water vapor condenses and falls as rain. San Juan receives an average of 1,330 mm (52 in) of precipitation each year. The mountain areas receive more rain than almost any other part of the United States, with more than 5,100 mm (200 in) falling each year at El Yunque. The southwestern coastal area generally receives the least rain in Puerto Rico and has a distinct dry season from December to March. Puerto Rico is sometimes struck by damaging hurricanes traveling from the east, especially from August to October.

D.

Plant and Animal Life

Most of Puerto Rico’s original forests were logged by the beginning of the 20th century. The government began a replanting effort in the 1930s. A commercial reforestation program has also created a modest commercial reserve of tropical hardwoods, including mahogany, ebony, laurel, and satinwood. Puerto Rico contains thousands of species of tropical shrubs and trees, including colorful bougainvilleas, poinsettias, and Sierra palms. There are giant coconut palms, mangroves, and bamboo trees. Orchids and giant ferns grow in the rain forest of El Yunque. Brilliantly hued poinciana trees border most of the older rural roads, lending the flaming red color of their blossoms to the landscape in June.

Puerto Rico has very little wildlife and few birds. The mongoose, introduced to control rats on the sugar plantations, is fairly abundant. There are nightingales and sparrow-like birds called gorriones. The coquí, a tiny tree frog that sings at night like a bird, leads many visitors to suppose that the island is filled with nightingales. In the waters surrounding Puerto Rico there are a number of different game fish, including tuna, blue marlin, bonefish, and amberjack.

Both the federal and commonwealth governments have stepped up efforts to preserve the island’s animal and plant life. Reserves of special note include the Caribbean National Forest, known as El Yunque, a tropical rain forest in the Sierra de Luquillo Mountains; Las Cabezas de San Juan Nature Reserve on the northeast coast; and the Carite Forest Reserve in the southeast. On the southwest tip of the island, La Parguera Natural Reserve has a phosphorescent bay that glows at night because of tiny sea creatures that give off a green light when their bodies are disturbed. The island of Culebra is home to the Culebra National Wildlife Refuge.