About half an hour south of Cancún stands the rickety wooden entrance sign to La Ruta de los Cenotes, a small highway leading into the jungle, populated only by the occasional souvenir stand or rental cabins. But the real attraction here is the cenotes: natural springs connected to the Yucatán Peninsula’s extraordinary underground river system. Ideal for swimming and snorkeling, the pools often feature diving cliffs, picnic grills, and maybe even a small zip line. Most forbid sunscreen and bug repellant to protect the water’s pristine quality. Top options include Las Mojarras, Verde Lucero, Boca del Puma, and Siete Bocas.