The Mystical Underground River In Mexico Where You Can Swim Beneath A Cave Full Of Crystals

Mexico's Yucatan Peninsula is a stunning area known for its white sandy beaches, delicious cuisine, amazing scuba diving, and great nightlife. What some may not know, however, is that it is also home to a deep dark secret ... a secret cave that is. Stretching approximately eight miles, these beautiful underground passageways (dubbed Rio Secreto, or secret river) have inspired exploration by experienced cavers and inexperienced tourists since opening to the public in 2008. Technically a closed cenote, it is one of the few underground rivers accessible to the public in Mexico, and is also the longest partially flooded cave on Mexico's Yucatan Peninsula.

Visits to the cave can only be conducted through a guided tour, but according to reviews, the tours are well worth it. Visitors can expect to walk and float along dark passageways (with a headlight of course) — however, the tour is not recommended for those afraid of the dark, swimming, or enclosed spaces. Inside, adventurers will find beautiful stalactite and stalagmite formations, dating back thousands of years, and tour guides provide a "deep dive" (pun intended) into a beautiful secret underworld. 

The cave system is located a short distance from Playa del Carmen, however, visitors can also pair it as a day trip from places like Tulum or Cancun. There are a few different tour companies offering excursions to the crystal cave — each one following much the same format. They typically provide equipment (wet suits, wet shoes, helmet with light, towels, and lockers), pick up and drop off location at hotels (depending on the resort location), a lunch, and an experienced tour guide. Visitors are also given a locker to store their personal items. If you do book a tour, be sure to book at least 48 hours in advance. According to one reviewer,  the transportation schedule is typically established the day before tours take place.

Interestingly, most who joined the tours have mentioned that due to the spiritual nature of the cave, a Mayan priest will preemptively bless your group, presumably to allow safe passage to the "underworld". Visitors will also have to hike a short trail to the mouth of the cave, so be sure to wear appropriate clothing. According to reviews, guides will be there to instruct explorers where to walk and provide explanations of the geology and history of the caves. However, due to the uneven surface of the cave, some reviewers mention that the tour is not recommended for those with mobility issues. Visitors also write about seeing bats or feeling fish, and that for a portion of the trip, your guide will ask everyone to turn off their headlamps, to experience the cave in its natural glory of blackness. Again, if you're afraid of animals, water, or the dark — this trip probably isn't for you.

Prices of the tours range depending on pickup location and which package you choose. For example on Viator, prices for the cave begin at $92 for adults and $46 for children, however, they also offer upgrades such as including the Tulum ruins, Puerto Morelos, a bike ride, a mountain climb, or a walk in a dry crystal cave, which of course cost more. Visitors can also book a tour directly through Rio Secreto's official website. Visitors to the river should also know that personal cameras are not allowed inside the underground portion. If you would like pictures, photo packages are available through your tour company, however many mention that they can be costly. 

If you choose to drive yourself to Rio Secreto, it is located on Highway 307 on the Kilometer 283.5 mark — less than 1.2 miles from Calica Port (though your tour will tell you the meeting point). The entrance is around five minutes from Playa Del Carmen, one hour from Cancun, and 50 minutes from Tulum. Though the Playa del Carmen Airport is the closest to the river, the Cancun airport offers more flexibility in terms of flights per day. Just remember however that even if you choose to drive yourself, you are still not allowed in the cave without a guide.