Of course it's not meant for swimming....it's the moon watch...there aren't any pools in space!
The Speedmaster is pretty water resistant, but it's not a dive watch, so you have to be a little careful. Both the Speedmaster and Daytona are rated at 100m (the whole rating system is ######ed because it doesnt mean you can go 100m under water), which is basically for splashing around, showering, swimming near the surface.
A watch like the Submariner is a diving watch so that you can play around without any concern.