You can see newborn baby turtles being released into the sea or swim with the dolphins at Xcaret Park; there are also ideal sites for skin-diving and snorkeling with the greatest variety of marine plants and animals to be found in Mexico, in places such as Isla Mujeres and Cozumel, although you may be more interested in visiting one of the region's many "cenotes" (pools of fresh water fed by underground streams) or exploring an underground river.