Tours from Isla Mujeres average around $90 (U.S.) per person. The Kolumbus Tours excursion is $115; $70 (ages 6-12). Reservations are required for all tours.
The boat trip is normally about 45 minutes one way but can take up to 2 hours if seas are rough. Kolumbus Tours offers an all-day trip that departs Tues., Thurs. and Sat. from the Marina Scuba Cancún dock, on Blvd. Kukulcán at Km marker 5 in the Hotel Zone. Daily departures (weather permitting) from Isla Mujeres are usually around 8 a.m. and can be arranged through Delfin Diving or Guadalupana Tours.