Revillagigedo Islands in the context of Volcán Bárcena

Colima, officially the Free and Sovereign State of Colima, is among the 31 states that make up the 32 federated entities of Mexico. It shares its name with its capital and main city, Colima.

Colima is a small state of western Mexico on the central Pacific coast, and includes the four oceanic Revillagigedo Islands. Mainland Colima shares borders with the states of Jalisco and Michoacán. In addition to the capital city of Colima, the main cities are Manzanillo, Villa de Alvarez and Tecomán. Colima is the fourth smallest state in Mexico and has the smallest population, but has one of Mexico's highest standards of living and the lowest unemployment. It is also the state with the highest murder rate per capita and one of the highest crime rates, due to its ports being a contested area for cartels.

Socorro Island (Spanish: Isla Socorro) is a volcanic island in the Revillagigedo Islands, a Mexican possession lying 600 kilometres (370 mi) off the country's western coast. The size is 16.5 by 11.5 km (10.3 by 7.1 mi), with an area of 132 km (51 sq mi). It is the largest of the four islands of the Revillagigedo Archipelago. The last eruption was in 1993.

Guadalupe Island (Spanish: Isla Guadalupe) is a volcanic island located 241 kilometres (130 nautical miles; 150 miles) off the western coast of Mexico's Baja California peninsula and about 400 km (220 nmi; 250 mi) southwest of the city of Ensenada in the state of Baja California, in the Pacific Ocean. The various volcanoes are extinct or dormant. In 2005 Guadalupe Island and its surrounding waters and islets were declared a biosphere reserve to restore its vegetation (decimated by feral goats) and to protect its population of marine mammals and birds. The island was a popular destination for great white shark cage diving before a tourism ban was put in place in 2022. Guadalupe Island is inhabited only by scientists, military personnel operating a weather station, and a small group of seasonal fishermen. The island is mostly arid and has very little surface water.

The two other Mexican island groups in the Pacific Ocean that are not on the continental shelf are the Revillagigedo Islands and Rocas Alijos. Guadalupe Island and its islets are the westernmost region of Mexico.