Go snorkeling at Yalkoo Lagoon a former natural Mayan harbor, in Akumal in the middle of the Riviera Maya, near Cancun and Playa del Carmen. The lagoon is a caved in cave system, full of fish. You snorkel through canyons while observing different type of fish, like sergeant mayor, parrot fish, neon fish, angel fish and the occasional barracuda or turtle.