Disney has a Dolphins In Depth program. They teach you about the dolphin and other aquatic wild life. They also provide information regarding ecology and the behavioral training that is going on at Disney. You then suit up in wet suits for a dolphin encounter in the Living Seas aquarium. The encounter is not guaranteed, if the dolphins do not want to participate, they don't have to. You do not get to "swim" with the dolphin, rather they just float in your arms. It was an amazing experience, I loved the tour.
If you really want to swim with them, Discovery Cove is your best option.