This is one of the most famous cenotes. It is a good experience, the water is crystal clear, and there is good space to snorkel. MXN $120 pesos was the entrance (Oct 2013), that's about 10 US dollars. About 2 or maybe 3 hours (tops) is enough to experience all there is to see as a snorkeler and relax. There are lockers available for an extra fee. If you visit another cenote I would also recommend Gran Cenote.
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