El Yunque Peak is located in Sierra de Luquillo mountain range, about a half hour drive east of San Juan, the capital of Puerto Rico. The area is administered by the United States Forest Service as Caribbean National Forest. It is the only tropical rain forest preserve in the US National Forest system, and is also one of the oldest forest preserves in the Western Hemisphere, having been originally set aside by the King of Spain in 1876. Parts of the forest receives nearly 200 inches of rain a year. Because of the area's long conservation history, it is the source of much scientific knowledge about tropical rain forests. In 1976 it was designated by United Nation's Man and Biosphere program as a Biosphere Preserve.
On clear days, the summit of El Yunque Peak is known to have great views over San Juan metropolitan area, the northeast coasts of the Island of Puerto Rico, and Vieques Island to the east. However, dense clouds often shroud the higher parts of the range, making the upper mountain area a cool refuge from the tropical heat below. There is a summit observatory built by Civilian Conservation Corps in the 1930's in the style of a Spanish castle, complete with a fireplace inside.
At the entrance to the National Forest on Highway 191 is the El Portal Visitor Center, a spectacular facility with much interpretative exhibits about rain forest ecology and conservation topics. Great views of the Atlantic coastline can be had from its decks.
El Yunque Trail is the direct route from Highway 191 to the summit. Its elevation gain is 1400 feet, over 2.6 miles. There are two trailheads about 300 meters apart on the west side of Highway 191. The main one is across the road from Palo Colorado Visitor Center, the other one is a little further up near Bano de Oro (old swimming pool built with boulders).
Carry a map with you as there are a few branch trails. The lower portion of the trail has old concrete pavement built in the 1930's. They help a lot because the soil is extremely wet and muddy most of the time. The middle and upper portions of the trail are quite rocky. There are several very well-built rain shelters along the way, providing cover as well as dry, hard floors.
No overnight camping in the wilderness areas. There are some campgrounds in the National Forest. Camping reservations can be made at the El Portal Visitor Center, on Highway 191 at the entrance to the National Forest.
Wear sturdy hiking shoes and carry a poncho.
http://www.fs.fed.us/r8/caribbean/ - Caribbean National Forest official site.