Cozumel is an island and municipality in the Caribbean Sea off the eastern coast of Mexicos Yucatán Peninsula, opposite Playa del Carmen. It is the largest inhabited island in the Mexican Caribbean region, measuring about 29 miles from northeast to southwest and averaging 9 miles in width. Cozumel is part of the state of Quintana Roo, Mexico. The island is separated from the mainland by the Cozumel Channel and is close to the Yucatán Channel. The largest city in Cozumel Municipality and the islands principal town and commercial center is San Miguel de Cozumel.