It should be emphasized that much of the tour is spent learning about dolphins and their facilities rather than actually wading in the tank, but my wife and I greatly enjoyed the tour. For example, we were told that when the Seas pavilion originally opened, there wasn't a separate section for the dolphins, but that was quickly changed - not because the dolphins were in any danger, but because they were the bullies of the tank, playing games such as spin-the-sea-turtle.
In the tank, we had a chance to both touch two of the dolphins (as seen in the photo) as well as give them hand signals and see if they responded. Officially, the tour is considered part of the dolphins' training - i.e., to teach them to be used to humans other than their trainers, and to respond to signals no matter who is giving them.
I understand that Dolphins in Depth normally sells out well in advance, but we were lucky because there were only us and another couple on the tour. Our in-water time was probably about 30 minutes - with more people, it probably would have been longer, but only to wait for others to have a turn.
I also note that our guides and the trainer - Stephanie, Jason, and Leslie - were also among the most enthusiastic and engaged CMs that I've ever encountered. (Stephanie taught us that the appropriate way to respond to an offered high five is with a fist and extended thumb - and yelling "Look! A turkey!" Nothing to do with dolphins, but...)