Playa is perhaps one of the best places to stay for diving: most of Yucatan’s dive sites are close by: the Mayan Riviera dive sites are a short boat ride away, the Cenotes are within driving distance and Cozumel can be reached in less than an hour by ferry that leaves from the main jetty in town. Also the Maya Temples are within driving distance. Most reefs are too far off-shore, so there is (almost) no snorkeling or shore diving.
Playa del Carmen, or ‘Playa’, is about an hour drive south of Cancun and is developing rapidly. Nevertheless, it is still much more laid-back than Cancun without the high-rises, less tourists and the fact that you can easily walk to most places in town. Playa has excellent (dive) facilities and fits multiple types of budgets.