This was our second exclusion with Calabaza. They are a quality operator, very professionally run and organized, and very fun people. I would recommend that anyone looking for a high quality snorkeling tour consider this operator.
They limit the number of participants to 12, and go where the ship's tours don't, so you avoid bumping into other snorkelers. It isn't cheap, but it includes booze (great rum punch), and a really good lunch. IF you want quality, you pay for it, and it's worth every penny.
Read Ardie12's full Celebrity Summit cruise review