The El Yunque National Forest is the only tropical rainforest in the National Forest System. At nearly 29,000 acres, it is one of the smallest in size, yet one of the most biologically diverse of the National Forests hosting hundreds of animal and plant species, some of which are not found anywhere else in the world.

El Yunque National Forest, formerly known as the Caribbean National Forest is a forest located in northeastern Puerto Rico. It is the only tropical rain forest in the United States National Forest System and the United States Forest Service.

This forest is commonly known as El Yunque, which may be attributed to either a Spanish approximation of the aboriginal Taíno word yu-ke which means “white lands”, or the word “anvil,” which is yunque in Spanish. The second-tallest mountain within El Yunque is also named El Yunque.

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.