Coco beach is further on north of Playa del Carmen and is more private and laid-back. If you want a quieter and more relaxed place to just simply lay out and get a great tan, then walk north until you reach Coco Beach. The farther you go north, the more deserted the beaches are likely to be. Otherwise, if you want to be more on the active side, try some snorkeling at Chunzubul reef, just outside Coco beach.