Puerto Rico is an unincorporated US Territory and the so-called unofficial 51st state. Located in the Caribbean. It is approx. 100 x 35 miles and is the smallest of the Greater Antilles (Cuba, Hispaniola, Jamaica and Puerto Rico). Its capital is San Juan.

Puerto Rico is an archipelago formed by the main island and 143 small islands, islets and cays, including Vieques, Culebra, Culebrita, Palomino, Mona, and Monito. Vieques and Culebra are also known by some by the Spanish Virgin Islands, formerly called the Passage Islands and also known as the Puerto Rican Virgin Islands.

The Puerto Rico Trench is about 1,750 km long and 100 km wide. The deepest point in the Atlantic Ocean, the Milwaukee Depth, lies within the Puerto Rico Trench, at a depth of 8,380 meters in the western end of the trench, about 160 km northwest of Puerto Rico.