SOLVED. Teen/Kids fantasy novel, people live under still water ponds, possibly shape shift? [s]

[Strange1]

I'm trying to remember a book I read probably 20 odd years ago.

It was a kids fantasy book I think it was set in England, kind of medieval times. There are these creatures that come out of still water ponds (Covered in mist I think) and drag people down to die. I think they could appear as an animals (An Elk or rabbit rings a bell) . It turns out that they are wearing a silver diving suit, they take the main kid down but instead of killing him they come to an underwater city and the kid and underwater kid work together to try to unite their people.

Any help would be much appreciated, it's driving me crazy!

[Tab]

Do you remember the cover?
Part of a series?

[Strange1]

I recall it being a stand alone book. I think I had it as a hardcover with no dust jacket so it was just a solid colour book, I do remember an image of a deer looking over a misty pond, It may have been in the book?

[Pamela]

This doesn't quite fit, but some of the elements are the same. Power of Three, by Diana Wynne Jones Power of Three

[Strange1]

Pamela wrote: "This doesn't quite fit, but some of the elements are the same. Power of Three, by Diana Wynne Jones Power of Three"

I think that's it!! :O
Thank you so much, you're the champion of this thread! haha

Now I can grab a copy of it and force it onto my kids.

[Pamela]

You're welcome. I really enjoyed this book. Diana Wynne Jones is one of my favorite authors.