Cenotes and cave diving in the Riviera Maya is one amongst the best diving experiences. The cenotes are geological sinkholes created by the long-term effects of rainwater percolating through the porous limestone aquifer that makes up much of the Yucatan Peninsula. Erosion of the aquifer forms caves and tunnels beneath the surface, and should the ground collapse into a water-formed cave, a sinkhole or cenote appears. Extremely clear water creates an incredible diving experience in a unique and beautiful habitat. It is important to note that cenote diving is an extreme, high-risk sport. Divers must be trained carefully; there is little or no room for mistakes.