We took an aquatic wonders and beach time tour. A tender picked us up and took us to a "submarine" like boat where we were able to observe corral and fish for about 45 to 50 minutes along probably a 400 yard route. Afterwards we spent 70 minutes or so on a nearby sand box island. This island was probably only an acre in size so nothing dramatic. But it was fine a beach. The water was easy to swim in and you could purchase drinks, snacks.
The boat ride to and from the ship was about 35 minutes each way.
For this one we visited Maya Cays with a lunch included. This had a very nice beach area for snorkeling as well as swimming. They had several varieties of animals - parrots, monkeys, bobcats, and other birds to look at as well as recreations of a Mayan temple. All very nicely done.
Lunch included an option of barbecue chicken or sea bass, along with salad and potatoes. I had the sea bass which was good.