There is a general uncertainty about the use of the terms island, islet and key, which are closely related but refer to different entities though at times those differences are subtle. Questions about the precise or mathematic dimensions of what is considered an island, islet or key (and also sometimes including atolls) arise from these doubts. The difference between these terms is basically the territorial size of each one. The size of the land mass determines the name. In order of size, from largest to smallest (at least in most of the Caribbean region) are islands, islets and keys. There are no atolls in Puerto Rico, although there are in other parts of the Caribbean. Atolls are another type of island structure that are smaller than islands, but may be larger than islets or keys, and sometimes even have small numbers of inhabitants. Another important difference is their geomorphic formation, which is based on the existence and development of coral reefs.

Puerto Rico is a combination of islands, and the main island — the largest and with the greatest territorial extension — carries the name that refers to the conglomeration. Under the jurisdiction known as Puerto Rico are approximately 140 insular geostructures, including islands, islets and keys of various sizes and magnitudes that border the coasts of the main island. Like the rest of the Caribbean islands, the geologic origin of the main islands of Puerto Rico is volcanic and they are therefore part of the same geostructure that makes up the insular arc of the Caribbean, which developed as a result of the subduction between the Caribbean and North American tectonic plates. This is also the case with islands that are secondary or adjacent to the main island of Puerto Rico, such as Vieques, Culebra, Mona and Caja de Muertos.

Vieques, with a total area of 84 km2 (32.4 square miles) and located some 13 km (8 miles) from the east coast of Puerto Rico, and Culebra, with a total area of 30.1 km2 and located some 27 km (17 miles) from the northeast coast of the main island, are considered municipalities of Puerto Rico because of the size of their territory and population. Mona Island, with an area of approximately 57 km2 and located approximately 70 km (43 miles) from the west coast of Puerto Rico, is essentially a nature reserve managed by the Puerto Rico Department of Natural and Environmental Resources (DRNA, for its Spanish acronym). The island is inhabited only by personnel from the DRNA Ranger Corps, who are responsible for protecting and preserving the island’s ecological diversity and its environment. Basically, Mona is a huge laboratory for scientific research, ranging from oceanography to biology, ecology, archaeology and geology, among other areas. Meanwhile, the Caja de Muertos Island is located 8 km (4.7 miles) off the southern coast of Puerto Rico and has a total area of approximately 2.4 km2 (0.9 square miles). Similar to Mona Island, Caja de Muertos is also a nature preserve, and in this case, it is managed under a special agreement between the DRNA and the Municipality of Ponce. Not all island structures necessarily have a strictly volcanic or tectonic origin separated from the geological and geomorphic origin of the main island (Puerto Rico). This is seen in the distribution of the kinds of keys found in Puerto Rico. While the keys along the north coast are fundamentally rocky promontories that were left separated from the main island of Puerto Rico due to various geologic processes and events, the keys of the south and southeast coasts are the result of deposits of sediment and organic material (mostly vegetation, and mangrove in type, and others from nearby deltas or estuaries) on coral reefs. Their sizes vary from a few square meters to 1 or 2 km2. These islands, islets and keys, which jointly form part of what is thought of as the singular unit called Puerto Rico, were connected by land to the main island. Through geologic and geomorphic events of various magnitudes and regularity, such as volcanic eruptions and diastrophic processes in general (epeirogenic or orogenic, such as, for example, tectonic or seismic events, respectively) along with a gradual rise in the sea level, resulted in the development and separation of these promontories along the coasts.

Some of these islands, islets and keys along the east coast of Puerto Rico are: Vieques Island and, under its jurisdiction, Chiva Key, Tierra Key, Jalova Key and Chiva Island; the island of Culebra and, under its jurisdiction, Luis Peña Key, Lobo Key, Lobito Key, Ballena Key, Norte Key and Culebrita Island. In Fajardo are Diablo Key, Icacos Key, Largo Key, Obispo Key, Ratones Key, Ramos Island, Palomino Island, Palominito Island and Lobos Key, among others; in Humacao: Batata Key and Santiago Key; and in Naguabo: Algodones Key.

Located on the south coast of Puerto Rico are: in Guánica, Don Luis Key, Terremoto Key, Caña Gorda Keys, Gilligans Island (Aurora Key), Honda Key and Ballena Island. Under the jurisdiction of the municipality of Guayama: Caribes Key and Mata Redonda Key. In the municipality of Guayanilla: María Langa Key and Mata Key. In Juana Díaz, Berbería Key. In Lajas: Bayo Key, Caracoles Key, Collado Key, Corral Key, Enrique Key, Mata Seca Key, Magueyes Island and Matei Island, among others. In Peñuelas: Caribe Keys, Palomas Key, Parguera Key and Río Key. In Ponce: Arenas Key, Cardona Island, Ratones Island, Frío Island, Caja de Muertos Island, Morillito Island, Gatas Island and Jueyes Island. In the jurisdiction of Salinas: Mata Key, Morrillo Key, Puerca Key, Barca Keys, Pájaros Keys and Ratones Keys. In Santa Isabel: Alfeñique Key, Cabezazos Keys, Caracoles Keys and Puerca Island.

On the west coast, in the municipality of Cabo Rojo: Fanduca Key, Ratones Island, Roca Ola and Roca Velásquez. In the municipality of Mayagüez: Desecheo Island, Mona Island and Monito Island. On the north coast, located in the municipality of Camuy: Peñon Brusi Key and Peñon de Afuera Key. In Arecibo: Los Negritos Key, Roca Cocinera Key, Roca Resuello Key and Tres Hermanas Key. In the municipality of Barceloneta: Tres Hermanos Key. In Bayamón: San Juan Island. In Carolina: Numero Dos Islet. In San Juan: Guachinanga Island, Piedra Island and Peñon de San Jorge Key. In Toa Baja: Cabras Island, Palomas Island and Las Cabritas Key. In Vega Baja: Cerro Gordo Island and the Garzas Islets.

Author: Harrison Flores Ortiz
Published: February 21, 2016.

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