Welcome aboard, Dawn! I'm so excited that you asked this question because my daughter and I still say that one of our very favorite Port Adventures we've ever experienced with Disney Cruise Line is our
dolphin swim at Blue Lagoon!
Now, in all fairness, I have not participated in the Atlantis Dolphin Swim or interaction, though I have had a wonderful time enjoying the beach day at Atlantis. But, I can certainly highly recommend the Blue Lagoon dolphin experiences. We did the full dolphin swim, which includes a push across the pool by the dolphins, which if you don't mind the extra cost, was the highlight of our time! But, the
dolphin encounter there is wonderful too. The groups are very small which means more interaction with the dolphins! There are wetsuits available at no extra cost which I enjoyed since it was a bit chilly in the water. However, going in July, you probably won't need to worry about that.
After the swim, we were able to stay on the island to explore, swim, relax, play on the beach, grab a bite to eat, and then take one of a few return boats back to the ship. I love that we didn't have to have a specific time to return, but could choose based on how the day was going. The island is simply beautiful, and the beach is much more relaxing and gorgeous than the smaller beach at Atlantis. However, if you're looking to do more touring and not so much beach time after your dolphin experience, Atlantis offers a few options with the dolphin swims to include touring their amazing resort. The aquarium there is spectacular!
So, you can't go wrong with either one, Dawn. It just depends on what else you want to do with the rest of your day after the dolphin swim. Have a great time!
Marcy