1. Rio Secreto Nature Reserve is an underground river system located in Playa del Carmen, Mexico. It is a natural wonder that consists of thousands of stalactites and stalagmites formed over millions of years. Visitors can explore the river system by wading through the crystal-clear water and marveling at the otherworldly rock formations. The reserve is also home to a variety of flora and fauna, including bats and blind fish. The tour is led by expert guides who provide information about the geological significance of the cave system and its cultural history.

2. The reserve is open daily from 9:00 am to 5:00 pm. The phone number for reservations and information is +52 984 803 9999.

3. Ticket prices vary depending on the tour package chosen. The basic package includes a guided tour, equipment, and a light snack and costs approximately $79 USD. Transportation to and from the reserve is not included in the ticket price but can be arranged for an additional fee. Visitors have the option of purchasing their tickets online or at the reserve on the day of their visit.