If you do only one thing while you're in Cancun, besides laying on the beach, do this. Rent a yacht for a day from Cancun Yachts Club and go to Isla Mujeres.
A group of 10 of us were recently down in Cancun vacationing and visiting a few friends who reside there. One of the biggest perks to having friends there is they've got the connections to get us some awesome things to do while we're there.
Our friend Jeremy was the one who hooked us up with Cancun Yachts Club and on a Sunday morning we all convened on Liquidity, our yacht for the day, and has the best time. Our captain was Don Julio (no joke) and his first mate was Tony, and between the two of them, they gave us a superb experience.
Liquidity was a good-sized yacht with lots of pillows on the front-end of the boat for people to sunbathe, and a large shade covered deck with a table and seating for those of us wishing to get out of the sun. All anyone had to do all day was relax and drink. Tony mixed any drinks we could have wished for as well as brought out snacks (chips and sandwiches) throughout the afternoon for us to nibble on.
Halfway to Isla Mujeres the boat dropped anchor briefly for us to snorkel in some reefs near Cancun, which was amazing. I've never seen so many schools of fish in one place at one time - the colors, the sizes, the numbers - it was fantastic. The only fly in the ointment was that we were forced to wear life jackets no matter your level of swimming prowess. Most people chaffed at that, but we eventually got over it when we realized there was no way around it. Apparently, it's a law punishable by having your boat license revoked if you got caught.
By the time we reached Isla Mujeres, we were all champing at the bit to get out of the boat again (it was extremely hot in Cancun this past summer) and cool off. It was perfect - the water is only waist-deep to shoulder-deep for at least a mile off the coast of the island. As soon as everyone was in the water, floaty pool toys came out, squishy balls and more served as the main entertainment of the afternoon as we floated around in the waves.
Finally, by late afternoon we'd had as much sun as we fair-skinned people could take and piled back on to the boat for the ride back to the marina. By 5 PM we were back on the dock and ready to shower off all the salt water and sunscreen we'd acquired over the day.
Without doubt this was one of the best experiences we had while in Cancun. We've done boats to Isla Mujeres before, but the Cancun Yachts Club took the experience to a whole new level. Bravo!