Swimming Games

Hi,

I'm a qualified teacher who is about to start teaching again, and I feel that all games that I play
with the kids are getting old, and with teaching the same kids year in year out I would like some
ideas for new games that I can play. Some games that I get the kids to play are ring-a-ring 'o'
roses, follow the leader, treasure hunt (sinkable toys on the pool floor), stuck in the mud.

So if there is anyone out there that is able to help me out that would be great.