Find That Book

I read this book in elementary school in the mid-90s in USA and I believe it was fairly newly published at the time. It was a middle-grade chapter book with a blue cover.

I don't remember a lot about it but parts of it were told from the point of view of a dolphin (or some type of cetacean) undergoing intelligence testing. Then at some point the dolphin might have escaped from captivity. That's all I remember...