Yep, all sounds depressingly, tediously familiar. I swim at a club for at least one or two miles per week. These are also my experiences (and I've been crashed into once or twice, albeit I haven't, thank heavens, been held underwater. WTH is the matter with people)?
These are my experiences:
Patriarchy chicken is much more prominent in swimming pools than on the street. They (men) will crash straight into you without thinking twice about it, and have done on more than one occasion when I refused to move, because apparently they didn't believe that I wouldn't.
There's a difference between being a fast swimmer and displacing more water than the QE2. There are plenty of regular (extremely good) male swimmers who manage not to do this. But the ones who do it are almost exclusively men.
I've had two men in the past 7 years try to 'mansplain' to me how to swim better. Neither were any great shakes themselves, whereas I'm a former competitive swimmer. This is despite the fact that I wear swimmer's earplugs, which these I simply point to, shake my head, and leave in.
They get very upset if you overtake. A bit like those slow drivers who hold you up then speed up as you overtake so you can't pull in. Then you set off on your next length while they bend double at the side, trying to regain their breath. In fact, the whole thing is a lot like those drivers (Goofy) who turn into absolute monsters behind the wheel of a car. Chlorinated water seems to have the same effect.
As soon as I get in the main sauna, which seems to be predominantly used by blokes, they'll engage me in conversation and be as friendly as pie.
It's weird.