(Source: there is a similar song called "Swimming Hole" in "The Kids' Campfire Book", Jane Drake and Ann Love, Kids Can Press, 1996, also in "Campfire Activities", Girl Guides of Canada, 1993.)
Swimming, swimming in my swimming pool
When days are hot when days are cold, in my swimming pool
Breast-stroke, side-stroke, fancy diving too.
Don't you wish you never had anything else to do, but....
Actions:
Swimming, swimming: swimming action
In my swimming pool: trace outline of pool
Days are hot: wipe hand across forehead
Days are cold: shiver
Breast-stroke: do the breaststroke
Side-stroke: do the sidestroke
Fancy diving: dive action
Repeat the song a number of times, leaving out each of the above lines one at a time but still doing the actions. The last verse should be all actions and no singing!