That's what I'm trying to figure out. I plan to get the RO 15450 and it is 50m with a screw down crown. I really want to be able to swim with it. I guess just wading in a pool with it would be fine, but I probably wouldn't take it in the ocean. Guess I'll have to hang onto my Explorer to take on vacations.
I can't imagine wearing a Royal Oak swimming or for similar activities. Notwithstanding the water resistance, those brushed surfaces are very easily scratched/scuffed and it will require a trip back to AP to be properly polished. Just not worth the risk IMHO.