We were also on the Fantasy last week and did the dolphin excursion in Cozumel. It exceeded our expectations - we did the "encounter" excursion with our 5- and 7-year-old. The enclosure where we played with the dolphins required us to wear life jackets and stand on a metal grating in about 4 feet of water (too deep for our kids to stand - we had to hold them, let them float, or let them hold on to the railing behind us). We got to touch the dolphin several times and each got to kiss, dance with, and pet the dolphin as it stretched vertically up to reach our hands. As I'm sure you've seen from other comments about these excursions - the pictures are extraordinarily expensive. We were able to get a CD of all of the pictures taken by the staff of both of our kids for $109. If you have someone extra in your party that can take their own pictures from the walkways, you can do that - they pay a lesser fee to be an "observer" but won't get in the water with the dolphins. I know you were asking about Costa Maya, but hopefully this gives you a comparison of what the Dolphin Discovery package was like in Cozumel.