If you book your excursion through
DCL you get the dolphin encounter which includes park admission. I think you stand on a platform in the water near the dolphins, think you get to do a dolphin kiss and handshake. (somone correct me if I am wrong here).
Dolphin swims cant be booked through DCL, you have to do that on your own. We did that one, and had to pay park admission in addition to the cost of the swim. Was an incredible experience though and very easy to do on our own.
The park was very nice, you will enjoy it.