Puerto Rico geographically belongs to the Greater Antilles, politically it more or less belongs to the United States, as it is freely associated to the Commonwealth of the United States. It is the most eastern of the four major islands of the Greater Antilles. Puerto Rico measures 177 by 36 kilometers or 8,959 square kilometers. To the north lies the Atlantic Ocean, to the south the Caribbean Sea. The capital is San Juan.
It can be conveniently divided into three geographical regions:
The limestone regions of Puerto Rico cover about 27% of the island's surface. Most of this is in the north of the country where all the large caves are found. The caves are not particularly long but many have large river passages. The large guano deposits are the source of histoplasmosis amongst cavers. The deepest and the longest cave is Sistema del Rio Encantado - VR=344 m and L=21,770 m . Cueva de Empalme is a 1,000 m long show cave, sometimes also called Rio Camuy Cave. But its most common name is Cueva Clara.