The island is located in the Caribbean Sea along the eastern side of the Yucatan Peninsula about 82 km (51 mi) south of Cancún and 19 km (12 mi) from the mainland. The island is about 48 km (30 mi) long and 16 km (9.9 mi) wide. With a total area of 477.961 km2 (184.542 sq mi), it is Mexico’s largest Caribbean island, largest permanently inhabited island, and Mexico’s third-largest island, following Tiburón Island and Isla Ángel de la Guarda.
The majority of the island’s population lives in the town of San Miguel (pop. 77,236 in 2010), which is on the island’s western shore. The municipality, which includes two small areas on the mainland enclaved within the Municipality of Solidaridad with a land area of 10.423 km2 (4.024 sq mi), has a total land area of 647.33 km2 (249.93 sq mi).