There are several islands along the Pacific Ocean in Mexico, a majority of which are in front of Mazatlan, and there are some islands in the Baja Peninsula as well. The only islands that I know of that are occupied with people and are Cozumel, Holbox, and Isla Mujeres, all of which are located off of the states of Yucatan and Quintana Roo in the Yucatan Peninsula. The other islands are uninhabited by cities or village but they tend to be inhabited by fishermen during fishing season. A lot of these islands are national parks so you cannot live there, but you can certainly visit.
(Hidden beach open to the sky on a Marietas Island off of Puerto Vallarta, Mexico, pictured.)