We did the swim with Dolphins at Dolphinarus. The place was nice, but there is absolutely nothing for observers to do other than watch. My 5 yr old who did not want to participate in the dolphin encounter was bored. Hindsight, I would have picked the Dolphin Discovery at Chakanaab park. They have a beach where observers can hang out.
This was the best stop for families. The beaches are very nice and there is a lot to do. There is not enough time on the island to really enjoy everything without being rushed. I would love to have stopped at this port twice like some of their other itineraries. The only real downside is the food. The food was subpar at best. You do not need to pre-pay for the tubes/floats or snorkel gear. They have more than enough. I would not waste money on the snorkel gear. There was nothing to see.