I have done both. I did the dolphin encounter at the Atlantis two summers ago while staying there. I was traveling with my sister who did not want to do the encounter so I did this alone. We were taken to lockers and given a wetsuit to wear over our bathing suits (and I wore my watersocks). We then were taken to a "room" for our dolphin lesson (I can't remember if we watched a video or it was just workers who talked.) I do remember being hot in the wetsuit during this. We were divided into groups of about ten to interact with our assigned dolphin. There was an older couple, a mother with twin teenage daughters and then a family with two younger kids in addition to myself in my group. I think I might have been the only one from the hotel in my group and the rest were from the cruise ships.
Our groups then headed to the water with our guides. We had two with us and they had us go in so that we were kneeling in the water. We got to pet the dolphin (my group had Echo). We were taught hand signals which we were called on to do one at a time to get Echo to do a trick for us (such as kiss.) I was lucky I was chosen to do an extra trick with Echo which was a high five. Overall, I think this was very well-organized and perfect for my first dolphin encounter, especially as I was a little nervous doing it on my own. I really enjoyed it.
This past summer, I did the dolphin swim at the Blue Lagoon while on the Disney Magic. My brother booked it and I did this along with him, my sister-in-law and their 3 kids (ages 7, 10 and 12). This was very different from the first encounter I did. I was expecting to wear wetsuits, but instead was given a life jacket that would help buoy me in the water (not sure how deep it was but definitely couldn't stand in it). Watersocks were not allowed. I was in a group of 10, the six of us, a father and son, and then another family of two. None of the kids had any trouble doing this, although my one 10 year old niece did get scared when she had to kiss the dolphin. We entered the water and were instructed to stay in a line, which was hard to do. We were called forwards, two at a time to interact with the dolphin (kiss it, dance with it, etc). We didn't have to learn any hand gestures. It was great fun. Then we were called out of the water and we sat up on the pier as we were called one at a time in the water for our dolphin swim. The guide explained to us what we had to do, lie in the water, our feet a certain way with our arms outstretched in front. A dolphin would come from behind and push us through the water. I was really nervous. But I went right after my seven year old nephew and he had no problems. I was tapped on the shoulder so it was my turn next and I had to go in the water. The dolphin wouldn't push me. Figures my luck. The girl told me it wasn't my fault, the dolphin was being fussy, so I had to give it a second try with my toes curled this time, and so did the adults who went after me). This time it worked. And it was amazing. But it was over so fast. You definitely can feel the dolphin's snout pushing your foot. So glad my brother wanted to do this excursion because I'm not sure if I would have ever signed up for this one if I had been in charge of picking it out.
So they are both very different, and yet I liked them both. Kids can do both, although I am not sure what the minimum age was for the dolphin swim (nephew was seven and he was old enough). For myself, I am glad I did the encounter first as I tend to get nervous. I think my nieces and nephews loved doing the swim and are glad that we didn't just book an encounter (although the two older ones had done an encounter when they were little but didn't remember it).
