What's the Name of That Book??? discussion

It's not the Ring of Endless Light but I think it did have the word "ring" or "circle" in the title.

Basically, the main character's father came back from an ocean expedition and he gives her a rock. They break the rock and discover a skeleton finger with a silver ring on it. The girl puts the ring on. I can't remember exactly how it worked but she begins to switch bodies with a dolphin named Bree who claims to have some disease called "nightsee" or something like that. She apparently got it from her mother. The point of view switches from the girl to Bree's but it's mainly centered on the girl. The plot involved getting all the sea mammals (dolphins and whales) together and bringing down some human threat.
I think there was also a subplot in which one of the dolphins ends up in being captured by a science lab (though he isn't harmed, they just teach him tricks and such). The girl and a friend steal the dolphin and literally carry it back to sea.
I'm fairly sure the book ends with the girl throwing the ring into the ocean. I read it around 1999 but it was a library book so it may be way older than that.

Sounds like A Circle in the Sea.

Nikki wrote: "Sounds like A Circle in the Sea."
Thank you! I've been searching for this for years and everyone kept pointing me to A Ring of Endless Light.

Breelynna, another book that you might like to try is Diane Duane's "Deep Wizardry". Young Wizards, Book 2 Deep Wizardry Check out it's synopsis and see if you think it sounds interesting.

(You don't need to read Book #1 first.)