Cedros Island is located in Ensenada Municipality, off the west coast of the Mexican state of Baja California, from which it is separated by Sebastián Vizcaíno Bay. It is northwest of Punta Eugenia in Mulegé Municipality - the westernmost point of the state of Baja California Sur mainland. It also lies north of Isla Natividad (off Punta Eugenia, and also part of Mulegé Municipality) from which it is separated by the Canal de Keller, and some from San Diego. The island has an area of , being the fourth-largest island in Mexico (following Tiburón Island, Isla Ángel de la Guarda, and Cozumel). It has a maximum length of approximately , and a maximum width of about .