El Yunque National Forest in Puerto Rico becomes part of the United States National Forest System as the Luquillo Forest Reserve.

In the United States, national forest is a classification of protected and managed federal lands. National forests are largely forest and woodland areas owned collectively by the American people through the federal government, and managed by the United States Forest Service, a division of the United States Department of Agriculture. The U.S. Forest Service is also a forestry research organization who provides financial assistance to state and local forestry industry. As of 2020, there are 154 national forests in the United States.

El Yunque National Forest (Spanish: Bosque Nacional El Yunque), formerly known as the Caribbean National Forest (or Bosque Nacional del Caribe), is a forest located in northeastern Puerto Rico. It is the only tropical rainforest in the United States National Forest System and the United States Forest Service. El Yunque National Rainforest is located on the slopes of the Sierra de Luquillo mountains, encompassing 28,000 acres (43.753 mi2 or 113.32 km2) of land, making it the largest block of public land in Puerto Rico.

The highest mountain peaks in the forest rises 3,494 feet (1,065 m) above sea level. The second highest mountain within El Yunque forest is also named Pico El Yunque. Other peaks within the national forest are Pico del Este, Pico del Oeste, El Cacique and El Toro, which is the highest point in eastern Puerto Rico and the Sierra de Luquillo.

Ample rainfall (over 20 feet a year in some areas) creates a jungle-like setting—lush foliage, crags, waterfalls, and rivers are a prevalent sight. The forest has a number of trails from which the jungle-like territory's flora and fauna can be appreciated. El Yunque forest is also 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.