My ENT custom plugs fit pretty tight in my ear. I believe the proprietary name of the plugs is "aquanot". There's bound to be some distortion with the PVS impression material they use(same stuff I use for crown and bridge work) but not really enough to notice. Some water will get in between the plug and your ear and form a thin film but it will stay there and get warmed by your body -- kind of like a wetsuit. If something is against your ear (like a full face helmet) they can start to hurt after a while They hurt to pull out but not to put in. Too many times in and out and your ear will be sore after boating. Overall, pretty comfortable if you leave them alone, super effective. Paddling out of the royal gorge on a cold windy day a few weeks ago I put them in because the headwind was blowing hard into my wet ears -- cold! They did the trick. I got mine for free so they're worth every penny but I would recommend getting a pair. A preventative measure like this might be covered by health insurance, even, esp. if you have documented hx of otitis media, exostotic growth, etc. Check it out.
They do, however, cut down almost completely on your hearing. For that reason, I only wear them playboating or downriver on play runs. Communication is too important on a creek and you're not supposed to be upside down anyway. Nystagmus is a little added insentive to brace effectively.
My ears are ringing right now, too, but it's cuz I just saw the Black Keys at the Ogden. They rocked SO hard! I feel like when I was young and bird hunting with my dad -- deaf from all the shotgun blasting.
I hope in the future Americans are thought of as a warlike, vicious people, because I bet a lot of high schools would pick "Americans" as their mascot. -Jack Handy