Well, first I cut off any excess bag with scissors... then I get rid of as much air in there as I can, fold down the bag, and clip it with a clothespin.
(I'm a bit particular sometimes...
)
Do you drive a vehicle with a manual or automatic transmission?
No freaking skiing!!!!!! Only because last time I went my leg ended up wrapped around my neck, that was on snow, I've never tried water, but I would try it.