Isla de Mona in the context of "Monito Island"

Puerto Rico (abbreviated PR), officially the Commonwealth of Puerto Rico, is a self-governing Caribbean archipelago and island organized as an unincorporated territory of the United States under the designation of commonwealth. Located about 1,000 miles (1,600 km) southeast of Miami, Florida, between the Dominican Republic in the Greater Antilles and the U.S. Virgin Islands in the Lesser Antilles, it consists of the eponymous main island and numerous smaller islands, including Vieques, Culebra, and Mona. With approximately 3.2 million residents, it is divided into 78 municipalities, of which the most populous is the capital municipality of San Juan, followed by those within the San Juan metropolitan area. Spanish and English are the official languages of the government, though Spanish predominates.

Puerto Rico was settled by a succession of Amerindian peoples beginning 2,000 to 4,000 years ago; these included the Ortoiroid, Saladoid, and Taíno. It was claimed by Spain following the arrival of Christopher Columbus in 1493 and subsequently colonized by Juan Ponce de León in 1508. Puerto Rico was contested by other European powers into the 18th century but remained a Spanish possession for the next 400 years. The decline of the Indigenous population, followed by an influx of Spanish settlers, primarily from the Canary Islands and Andalusia, and African slaves vastly changed the cultural and demographic landscape of the archipelago. Within the Spanish Empire, Puerto Rico played a secondary but strategically significant role compared to larger and wealthier colonies like Peru and New Spain. By the late 19th century, a distinct Puerto Rican identity began to emerge, centered on a fusion of European, African, and Indigenous elements. In 1898, following the Spanish–American War, Puerto Rico was acquired by the United States.

The geography of Puerto Rico encompasses the geographical features of Puerto Rico, a Caribbean archipelagic and island nation centered around a collective identity based on its land, history, ethnicity, culture, and language, and organized as a self-governing unincorporated territory of the United States. Located between the Greater and Lesser Antilles in the northeastern Caribbean Sea, east of Hispaniola, west of Saint Thomas, north of Venezuela, and south of the Puerto Rico Trench, it consists of the eponymous main island of Puerto Rico and 142 smaller islands, islets, and cays, including San Juan Islet in the north, Vieques and Culebra islands in the Virgin Islands, and Palominos island and Icacos cay in La Cordillera nature reserve in the east, Caja de Muertos island in Caja de Muertos reserve, and Caracoles and Media Luna cays in La Parguera reserve in the south, and Mona, Monito, and Desecheo islands in the Mona Passage in the west.

Measuring 177 km (110 mi; 96 nmi) in length and 65 km (40 mi; 35 nmi) in width with a land area of 8,868 sq km (3,424 sq mi), the main island of Puerto Rico is the 4th largest in the Caribbean, 29th in the Americas, and 81st in the world, making it the 170th largest country or dependency by surface area. With 3.2 million residents, it is also the 4th largest in the Caribbean, 4th in the Americas, and 31st in the world, making it the 136th largest country or dependency by population.

This is a list of islands of Puerto Rico.

The Commonwealth of Puerto Rico has over 143 islands, keys, and islets. Only the main island of Puerto Rico (3,424 sq mi [8,868 km2]), and the islands of Vieques (51 sq mi [130 km]), and Culebra (10 sq mi [26 km]) are inhabited. Mona Island (22 sq mi [57 km]) has personnel from the Puerto Rico Department of Natural and Environmental Resources (DNER) stationed year-around but no private citizens inhabit it (other than overnight camping guests and nature enthusiasts). Caja de Muertos Island (0.58 sq mi [1.5 km]) is also a DNER Nature Reserve, while Desecheo Island (0.58 sq mi [1.5 km]) is a National Wildlife Refuge administrated by the US Fish and Wildlife Service.

Mona and Monito Islands Nature Reserve (Spanish: Reserva Natural Islas Mona y Monito) consists of two islands, Mona and Monito, in the Mona Passage off western Puerto Rico in the Caribbean. Mona and Monito Islands Nature Reserve encompasses both land and marine area, and with an area of 38,893 acres it is the largest protected natural area in the Commonwealth of Puerto Rico (El Yunque National Forest, with 28,434 acres, is the largest in the main island of Puerto Rico). Much like the Galapagos Islands in the Pacific Ocean, the Mona and Monito Islands reserve represents a living laboratory for archaeological, biological, geological, oceanographical and wildlife management research.