Welcome aboard, Shelly!
My daughter and I had the most wonderful experience during our Dolphin Swim during a Disney Cruise Line Port Adventure. She still has the photo up on her bulletin board in her room of her with the gorgeous dolphin that pushed her on the thrilling ride across the water. What a memory!
You can't go wrong with a dolphin swim in either of those three ports, Shelly. But, to help you decide, I'd suggest considering a few things. I highly recommend a dolphin "swim" over a dolphin "encounter" or "experience" because it will include that amazing push or pull across the water. Since your daughter is six years old, she is able to participate in those full dolphin swims at both
Cozumel and
Grand Cayman. In Jamaica, she'd only be eligible for the dolphin encounter, since the swim begins at age eight.
Are you planning to do an adventure in each port of call? If so, see if there are any "must-do's" in Cozumel or Grand Cayman, and if so, plan the dolphin swim in the other port. In Jamaica, you absolutely must take one of the Port Adventures that includes a visit to Dunn's River Falls. It is the quintessential Jamaican experience for your whole family. There is a combo tour that includes the
Dolphin Encounter and Dunn's River Falls, but if possible, I highly recommend the dolphin swims in the other ports instead so she can make the most of the experience!
I hope that helps as you plan, Shelly! Please stop back with other questions as you count down to your fall cruise with Disney!
Marcy