We did this on our own in December and LOVED it! We did the dolphin encounter and then a separate manatee encounter. The manatee encounter was more laid back and they allowed you to just hang with the manatees for over half of the experience. My daughter is 8, but the size of a 6 year old and needed held the whole time we did the dolphin encounter. The platform that you stand on in the dolphin area is a little deep and the small waves were a little hard to handle. They wanted you to stand on the platform at all times, but the waves kind of pushed you out, so you had to hold onto the side. It was just a tad difficult to hold onto the side and hold onto my daughter at the same time, but it was certainly able to be done. Pictures there were super expensive, so we passed. They really want you to buy them though! The sea lion show there was just okay. The pool is very nice. The beach area is small, but there is a ton of sand to play in near the snorkel area and beach chairs and umbrellas to sit under. There are also iguanas walking around, which was cool. The snorkeling was enjoyable, but difficult to first get out to b/c you have to go down some steps and the first area is difficult b/c of the waves. Once you get out, it's great!
If taking little kids, I would recommend taking sand toys. We liked it so much that we are going back next March and will do the manatee encounter again, snorkel, and explore some more of the park. It's a neat place! Let me know if you have any other questions.