Project Dolphin was an original plan thought up of back in 2004/2005.
The project would have involved the creation of a new themed area or the redevelopment of several existing areas to create a place where guests could have experienced "once in a lifetime" experiences. It would have been offered similar experiences to what you can do at Discovery Cove in Folrida
It was a very ambitious project but was shelved as the development team felt at the time that Alton was not ready for such a project.
The only images that remain online that show some of the plans are these ones below, all taken from Rollercoaster Pro