My daughter and I have discussed that when we swim her hair flows like a river behind her, while mine floats like a cloud around me.  I think it illustrates how my hair is fine while hers is coarser.

I confess to sometimes swimming with it loose.  If I braid it before wetting, I'm always worried that some part of the braid won't get wet and absorb the chlorine instead.  I hate the way the cold water feels on my back when wetting it, so I usually bend forward, which tangles the loose hair enough it becomes difficult to braid.  So I swim with it loose and then use lots of detangler and conditioner to unsnarl it before washing. 

Unless I'm swimming in the ocean.  Then I blop on lots of conditioner and braid it.

Apply conditioner first.  Uhm...I don't actually remember if the advice is to rinse out the conditioner first but I assume so.  It still seals the hair somewhat so that your hair doesn't soak up all the chlorine or salt water.  I don't know if it actually works.  I forgot to test it last summer, the only time in ages when I went swimming.