Puerto Rico is the smallest and easternmost island in the Caribbean island chain known as the Greater Antilles. The island is mostly mountainous or steep hills. This rugged geography has meant that Puerto Rico's close to 4 million inhabitants pursue industrial activities because agriculture is so difficult on the island. Today, less than 10 percent of the land is used for farming, according to the U.S. Central Intelligence Agency's (CIA) World Factbook.
Puerto's Rico's interior is dominated by the mountain chain, which locally is called the Cordillera Central. This chain of mountains runs east to west across the entire island. The ranges themselves are called La Cordillera Central, La Sierra de Cayey, La Sierra de Luquillo and La Sierra Bermeja. Many of the highest peaks are more than 4,000 feet, and Puerto Rico's tallest mountain is Cerro La Punta at 4,390 feet, according to City-Data.com.
Originally formed by the erosion of the inland mountains, Puerto Rico's coastal plains extend generally about 10 miles inward on the northern coast but only about 2 to 8 miles on the southern coast, according to Puerto Rico Encyclopedia. These plains are predominantly sandy beaches. Just off Puerto Rico's coast is the Mona Passage, a large shipping channel that provides a safe course to the Panama Canal from the Atlantic. San Juan is also one of the biggest and best natural harbors within the Caribbean, according to the CIA World Factbook.
Along Puerto Rico's northern coast lies the Aguada-Loíza karst region. According to Watersheds.org, a karst area is formed when sedimentary rocks are eroded by groundwater. Caves, tunnels and sinkholes are left after the rock is washed away. Puerto Rico's was formed over centuries by the Río Camuy, the third-longest subterranean river in the world. This river formed an extensive cave system, one of the largest in the Western hemisphere, in fact. This line of karst features runs from Aguadilla in the west to a minor haystack hills formation in Loíza, which is located just east of San Juan.
Besides Puerto Rico's Río Camuy, more than 50 waterways run through the island, though none are large enough for a large boat, according to City-Data.com. Most of the rivers flow northward and empty into the Atlantic Ocean. Puerto Rico's lakes are mostly reservoirs created from the dams of blocked rivers, which also provides the island with some power from hydroelectricity.
