Swimming with the dolphins is an experience at Discovery Cove, an "all-inclusive day resort" owned and operated by Seaworld Parks & Recreation. It is a separate park from Seaworld Orlando.
www.discoverycove.com
Admission to Discovery Cove can include the dolphin swim (where prices are generally $225 and up, depending on the season) or "day resort only" (access to all the same park features and attractions but no dolphin interaction).
Meals (breakfast and lunch), snacks (all day), beverages (including alcohol), parking, a 6 x 8 group photo, sunscreen, snorkels, shampoo, conditioner, towels and lockers are all provided with either type of admission. The dolphin swim includes a 30-minute session in the water in small groups of approximately 8 people (you will be combined with another small group to make up that number if needed) at a specific time assigned at check-in. You will have the opportunity to pet, feed, kiss, and "swim" (where you hold the fin and back of the dolphin as they take you for a swift drag through the water....deep or shallow, your choice) with the dolphin. There is a photographer in the water to capture multiple photos of each participant during each phase of the interaction. Those photos are an additional cost and can be purchased either by the print or in a package (some which include a CD of all images). DVD's of the swim are also available for purchase.
Other areas of the park are a free-flying aviary with an assortment of tropical birds (food is provided for you to feed them), a sand beach with a lengthy tropical lazy river (with a cave at the entrance and varying depths throughout), the Grand Reef where you can snorkel with various fish (and also alongside sharks, with a glass wall for obvious safety reasons), and the Freshwater Oasis where you can swim alongside Asian Otters and watch marmosets playing in the trees (there's also an in-water seating area with sunken loungers to enjoy a beverage or snack while keeping cool). From time to time, there are also animal encounters with DC staff (we have met a sloth and an armadillo).
You cannot purchase the dolphin experience at DC a la carte. But...your DC admission will include 14 days admission to both SeaWorld and Aquatica (SeaWorld's waterpark), which you can use either before or after your DC day (or a combination thereof).
Prices for DC tend to go up as the dates get closer, with the remaining tickets increasing in cost as the others are sold. You are generally best to purchase early as a result.
Let me know if you have any other questions! We have been three times.....twice with the dolphin swim, once without.....and it never gets old. Its a full day park that is well worth the $$$'s!