Our 2yo had grommets in and adenoids and tonsils out all at the same time - not a happy chappy for a couple of weeks

We've been using Docs Pro Plugs (
http://www.proplugs.com/swimming.shtml) in conjunction with the neoprene headband when swimming.
Just the Pro Plugs when in the shower, wee bit of vaseline to help them stick. Pull up the top of the ear to help them seat.
Boyo aint too stressed by them at all...