El Yunque

Located on the Caribbean Island of Puerto Rico in the Greater Antilles group, the El Yunque National Forest is the sole tropical rain forest in the U.S. National Forest System. The forest’s relatively small 28, 000 acre size belies its importance. It differs significantly from all the other U.S. National Forests because of its year-round tropical climate and immense biodiversity.

http://www.fs.fed.us/r8/caribbean/about/index.shtml