When I was at school (a long time ago) I had a teacher that read us fantasy books, and there's one that has stuck in my mind that I'd like to track down and read again. It would have been around 1983-84, the story revolves around a girl who has to go on some quest that took her into a lake, the fish had a community down there and they could all talk (the pike was the bad guy). Before she could go, she had to swim to the middle of a lake (possible a different lake) to retrieve some magic water lillies that could be made into a mask that would allow her to breath underwater. That's about all I can remember. I've been trying to find out for years, does anyone recognise this and know what it's called?

The Stream That Stood Still by Beverley Nichols

Awesome, thanks mate. My little girl will love this!

Glad to help.