El Yunque National Forest (), most commonly known as El Yunque, is a tropical rainforest with cultural, historical, ecological, scientific, and recreational features in the Sierra de Luquillo mountain subrange in the northeast of the main island of Puerto Rico, managed by the U.S. Forest Service since 1903. Situated immediately outside the urban core of the San Juan metro area, within east of the Old San Juan historic quarter, Condado and Isla Verde resort areas, Hato Rey business center, and SJU airport, the forest is mostly concentrated in the municipalities of Río Grande, Luquillo, and Naguabo. In addition to being the only tropical rainforest in the U.S. National Forest System, it is the easternmost, southernmost, wettest, and most biodiverse national forest in the U.S.
Covering 28,516 acres (44.556 mi2) of the Sierra de Luquillo mountain subrange, El Yunque is geologically composed primarily of volcaniclastic rocks, mostly basalt and andesite fragments, with significant igneous intrusions of quartz diorite on its the south-central part, all formed underwater during the Early to Late Cretaceous epochs. It has 8 peaks reaching more than 900 m (2,953 ft), of which 5 exceed more than 1,000 m (3,280 ft), including the El Toro, El Yunque, and Los Picachos peaks. It is the source of 10 rivers and 7 watersheds fed by 3,860 mm (152 in) of yearly average rainfall, mostly drained by the Blanco, Espíritu Santo, Loíza, and Mameyes rivers. It has six distinct forest types, namely the gallery forests along waterways, the secondary and tabonuco lowland forests, the palo colorado and palma de sierra mid-elevation forests, and the roblecillo and guayabota cloud forests. These are habitat to 164 vertebrate species and more than 1,000 tree and plant species.
With about 1.2 million visitors annually, El Yunque is equipped with the El Portal de El Yunque visitor and exhibition center, and the Caimitillo, Palma de Sierra, Puente Roto, Quebrada Grande, and Río Sabana picnic and recreational areas. It has 13 hiking trails of varying difficulty covering about , including the La Coca, Big Tree, La Mina, El Yunque, Mt. Britton, and Trade Winds trails. These not only lead to ponds, streams, and/or waterfalls, some of which feature boulders with pre-Columbian petroglyphs made by the Taíno, who revered the forest as a spiritual site, but they also end at observation towers and platforms on summits, which, depending on cloud cover, offer panoramic views of not only the forest and the mountain subrange, but also of nearby municipalities from Bayamón and San Juan in the west to Vieques and Culebra in the east. The highest visitor parking areas in the forest are near Mt. Britton trail at an elevation of about 760 m (2,493 ft).
El Yunque is a UNESCO Biosphere Reserve, an area protected to demonstrate the values of conservation, operating as an experimental forest under the Luquillo Experimental Forest, which provides scientific research on climate, geology, soils, water resources, flora, fauna, and ecology. Among its investigation stations is the Iguaca Aviary, dedicated to the preservation of the Puerto Rican parrot, a critically endangered species. Additionally, specific areas within the forest are further protected for their scientific, ecological, recreational, and/or scenic value, including the El Toro Wilderness, Baño de Oro Research Natural Area, and Icacos Wild and Scenic River.
Etymology
El Yunque is the name of the mountain peak, Pico El Yunque, the name of the forest, and, colloquially on some occasions, the name for the entire Sierra de Luquillo range. El Yunque most likely comes from or relates to the Spanish word yunque, meaning anvil. This name references the relatively high and flat shape of the Sierra de Luquillo range when observed from the north (El Yunque Peak) or the south (El Toro). It is also said that the Spanish name might have been influenced by the native names for the mountain: Yukén or Yuke possibly meaning "white land", and Luquillo or Yukiyu, another name for the spirit or deity Yokahu and also the name of a legendary cacique, Loquillo. It is not known whether the mountain gives its name to the range or vice versa.
In Puerto Rico, the name of El Yunque is often used in an exchangeable manner between the mountain, the mountain range, and the federally protected forest. While the massif is located within the municipality of Río Grande, El Yunque National Forest today extends over 11,000 hectares (28,000 acres) through the municipalities of Río Grande, Luquillo, Naguabo, Ceiba, Fajardo, Canóvanas, Las Piedras and Juncos, in order of total cover.
History
The area of the El Yunque National Forest has been notable since the pre-Columbian era. The forest today is home to several archaeological sites related to the indigenous Taínos, such as the Río Blanco petroglyphs, although no evidence of permanent settlement has been found in the area, which suggests that it was possibly avoided and most likely considered sacred. El Yunque forest is renowned for its unique Taíno petroglyphs. It is said that indigenous people believed that El Yunque was the throne of their chief god Yúcahu, so that it is the Caribbean equivalent to Mount Olympus in Greek mythology.
The Spanish began the conquest the island of Borinquen in 1493, and gold was soon found in the Fajardo and Blanco Rivers in 1509, which sparked interest in gold mining in the area. By 1513 there were gold mines in both river areas and gold was soon found in other rivers of the mountain range such as the Sabana, Prieto, La Mina, Mameyes, Espíritu Santo and Canóvanas rivers. The period of gold mining in the area, however, ended in 1530 when miners and settlers started being attacked by rebelling Taínos, and the area would not be settled again until the 17th century. The area where the El Portal Rainforest Visitor Center is located used to be the site of a coffee plantation named Hacienda Catalina. Coffee was introduced and cultivated in the slopes of El Yunque in the 1730s but the area remained relatively untouched until the 19th century when the lowland forests were exploited for timber and cut down for the development of agriculture, which attracted the attention of the Spanish Crown. The forest during this time was part of the Crown lands of Puerto Rico, and in 1853, the Spanish government sent foresters from the Inspección de Montes (the Spanish Forest Service) to survey the land. Due to the rapid population growth in the island and the poor farming practices of the impoverished European immigrants of the time, the forest region was formally set aside in 1876 by King Alfonso XII of Spain to preserve the soil and water resources and regulate the timber industry in the region. This makes El Yunque one of the oldest reserves in the Western Hemisphere, only four years younger than Yellowstone National Park. The Spanish Crown ceded Puerto Rico to the United States in 1898. At the time, most of the original forests in Puerto Rico had been either cut down or burned down, and the highlands of the Sierra de Luquillo contained the last remaining tracts of untouched forest in the island. President Theodore Roosevelt set aside the previous Crown Lands of the El Yunque area, and the Luquillo Forest Reserve was established on January 17, 1903, by the United States General Land Office with . It became a National Forest in 1906 and was renamed the Caribbean National Forest on June 4, 1935. The forest was still used for timber during the First and Second World Wars and several military installations such as radars and communications infrastructure were installed in the forest, particularly on the highest peaks, such as the early-warning radar site installed in Pico El Yunque to observe and protect against possible incursions by German aircraft and submarines.
The Caribbean National Forest was designated an Insular Wildlife Refuge by the US Department of Agriculture in 1946, and reforestation efforts were also established between 1934 and 1948 to revitalize the parts of the forest that had been formerly lost due to human activity. The Luquillo Experimental Forest was established in 1956 to promote scientific research and expand conservation efforts for the critically endangered Puerto Rican parrot and the recently discovered yet endangered elfin woods warbler. Most of the recreational infrastructure was developed in the 1980s, and the field offices were moved to their current location in 1981. The National Science Foundation established El Verde Field Station in 1988 under an agreement with the US Forest Service as a primary site for the Luquillo Long-Term ecological Research (Luquillo-LTER, now managed by the University of Puerto Rico, Rio Piedras) to support scientific research of tropical ecosystems due to the occurrence of five out of six of Holdridge's life zones and forest types. The forest was heavily damaged by Hurricane Hugo in 1989 and Hurricane Georges in 1998, and it is estimated that only 23 individual parrots remained in the wild afterward. Between 2000 and 2002, 35 captive parrots were released into the wild as part of a program to save the critically endangered bird. An executive order signed by President George W. Bush on April 2, 2007, changed the name of the Caribbean National Forest to El Yunque National Forest, better reflecting the cultural and historical feelings of the Puerto Rican people. Hurricanes Irma and Maria caused deforestation, landslides and heavy damage to the forest and its infrastructure in 2017, drastically reducing the Puerto Rican parrot population once again. By 2021, the population had begun to recover, and the captive population's reproduction rates also doubled under the supervision of the Fish and Wildlife Service.
The Portal Rainforest Visitor Center reopened at the end of 2021, after being reconstructed following Hurricane Maria. Additionally, the Conservation Trust of Puerto Rico (Fideicomiso de Conservación de Puerto Rico) also maintains a visitor center and contact station managed by its nonprofit unit, Para la Naturaleza. As of 2026, visitor numbers have sharply increased in recent years after Hurricane Maria and the COVID-19 pandemic, prompting proposals to charge admission fees to El Portal and La Mina Recreation Area, the most visited sections of the national forest.
Climate
Puerto Rico has a tropical climate, specifically a tropical rainforest climate, while higher elevations over border on a subtropical highland climate. There is no distinct wet or dry season in El Yunque; it rains year-round. The temperature and length of daylight remain fairly constant throughout the year. The average temperature in the summer is high and low and in the winter high and low, Temperatures can drop below on clear nights during the winter, but never below freezing. All of these factors provide a year-round growing season.
Ecology and conservation Its ecosystem is specifically surveyed by the Management Team of Ecosystems (Equipo de Manejos de Ecosistemas), which is led by Pedro Rios. Due to its location in the northeastern part of Puerto Rico, the incoming trade winds from the Atlantic Ocean bash into the mountains, leading to an excess of rainfall registered at about per year. This process is called orographic lift and accounts for the intense rainfall and constant cloud presence in this mountainous region. This constant cloud cover and persistent winds produced by the adiabatic process of air particles rushing up through the mountainside have affected the morphology of El Yunque, but the most effect has been on the bosque enano or dwarf forest.