Ariel's was the Beach Club's high-end restaurant. Yachtman's Steakhouse emphasized meat, Ariel's emphasized fish, to go with the hotel's nautical theme. I seem to remember that it was very blue, had lots of aquariums - a more whimsical version of Epcot's Coral Reef restaurant. It closed in 1994 or 1995, I think (anyone?).
If you type Ariel's in the search function, you'll get a few interesting threads in which guests shared their experiences at Ariel's.