Haven't done the Dolphins in Depth myself, but there is info on it on the Members' website. It's under Special Members Offers (which is a category under Member News). Here's what it says:
Disney's Dolphins in Depth and Dive Quest
"Disney's Dolphins in Depth" program at The Living Seas at Epcot® allows you not only to explore the world of Atlantic bottle nose dolphins, but to actually see research projects in progress. You'll have a unique opportunity to be up close and personal in the water with our two resident dolphins! You don't need to swim or be scuba certified to enjoy this program, but you do need to be 16 or over to participate.
"Dive Quest" allows certified open water scuba divers to enjoy a Disney diving adventure. Imagine a salt water dive with 203 feet of visibility and over 4,000 animals native to the Caribbean swimming with divers. Tropical fish, sharks, stingrays, giant green sea turtles, and plenty of coral for divers to enjoy is just part of the fun. All levels of SCUBA certification are accepted.
DVC Members receive a 15% discount for "Dive Quest" and "Disney's Dolphins in Depth". Both programs include a limited edition tee-shirt, and "Disney's Dolphins in Depth" includes a videotape of your experience and refreshments. For more information and to make reservations, call (407) WDW-TOUR. Identify yourself as a Disney Vacation Club Member and show your Member card or Walt Disney World® Resort ID, which identifies you as a Member at the time of the program. Note: program costs do not include admission to Epcot® programs are subject to change and availability. All proceeds go to the Disney Wildlife Conservation Fund.
HTH make you decision.