El Yunque National Forest, formerly known as the Caribbean National Forest is located in the rugged Sierra de Luquillo, 40 km southeast of San Juan. It is the only tropical forest in the United States National Forest System. Originally set aside in 1876 by the Spanish Crown, the Forest represents one of the oldest reserves in the Western Hemisphere. It has over 240 species of trees and plants. It receives rainfall up to 240 inches per year.