A question for water lovers

Hi everyone,

I was doing some searching through the forum for info on using one's SMP for water activities. Now I know it's a dive watch, but last year I had to have mine overhauled :sad: because there were spots on the underside of the crystal. They were faint, but similar in appearance to water spots you might get on your windshield. There was no rust in the movement or anywhere else, so I have no idea how it could have happened.

These days I may swim or snorkel with my SMP but I'm still a bit skittish. Years ago when I used to dive I had a Seiko auto and never had a problem, even at 100+ feet down. I have read that swimming might be bad due to the pressure created by the hand entering the water with force. How tightly do you guys screw down your crown/helium valve? Again, any thoughts or advice is much appreciated.