So according to the Core Rulebook, swimming in stormy water requires a DC 20 swim check, and you can't take 10. That's the toughest swim DC listed there.
However, when talking about creatures with swim speeds, it says "It gains a +8 racial bonus on any Swim check to perform a special action or avoid a hazard."
What special actions or hazards require swim checks? How high would those DCs be?
I'm asking because I made a half-elf PC with the Water Child alternate racial trait from the Advanced Race Guide, which gives a +4 racial bonus to swim and lets me take 10 in all circumstances. So once I hit +10 bonus, I'll be able to take 10 to hit a DC 20 without rolling. So is there any reason to take more skill ranks in swim after I'm at +10? It just seems like I'll able to insta-succeed on any swim check, if 20 is the highest DC.