The Commonwealth of Puerto Rico consists of the main island, and a series of smaller islands, mostly off its eastern coastline.
Volcanic in origin, the big island is mountainous through its heart. The most significant mountain range "Cordillera Central" contains Puerto Rico's highest point; Cerro de Punta at 1,339 m (4,393 ft).
The coastal areas, north and south are mostly lowlands, fronted by hundreds of miles of sandy beaches.
Rocky cliffs stretch across parts of the northern coastline, and in the north, Puerto Rico's so-called (karst region) contains small caves, caverns, rain forests, sinkholes, waterfalls and underground rivers.
A dozen (rather small) man-made lakes are scattered about, and more than 50 rivers drain the island.
The Puerto Rico Trench, some 70 miles directly to the north, is the largest and deepest trench in the Atlantic Ocean at 8,400 m (27,600 ft).