Tulum is where the caves are, though after my last trip a couple of months ago, I am tempted to give Puerto Aventuras, where I had based myself a couple of times before, another go. Tulum has changed a lot in the 22 years since I first visited. It's pretty crazy now. As a dive shop owner put it, "Tulum is the only place I've lived where it's easier to get your chakra fixed than your boiler."