My wife was looking for a catamaran trip that only stays on the water and doesn't dock anywhere. She enjoyed just relaxing on the water and she would like to do that and only that. It is our second time to Cancun and our first to Temptation.
I'm not aware of any that meet your criteria. The booze cruise usually stops on Isla Mujeres for a couple of hours. The Boobs Cruise stops long enough for lunch but is a party atmosphere not relaxing. My best suggestion would be to try USA Transfers and look at the tours they offer. It may have to be a half day snorkel trip in which you stay on the boat and don't snorkel. Otherwise, there's private charters, but those are pricey unless you get others to share it with you.
