Cancun and Cozumel has some of the best diving around whether it be traditional reef diving or more adventurous cave or cenote diving.  Whether you are touring around the Mayan ruins on the Yucatan peninsula or snorkeling in the Riviera Maya, Eastern Mexico is a great place to visit.  Make sure you hit Senior Frogs and the Bulldog Cafe for some drinks.  The Westin Regina, Flamingo and Tucancun Beach are some good places to stay while visit Cancun.  Enjoy the beaches and aqua waters.