Swimming is very dangerous in this game and I always found it a bit weird, probably related to mobs idk...
Well, why don't allow naked chars to swim easily with a minor cost of stamina? While keeping the system as it is for dressed chars.
Would be a good way for escaping bad situations for new players and the chance to escape fights later on at the cost of dropping all your clothes .... yeah the problem would be what to consider bad for swimming, only clothes, or also weapons, rings, etc... maybe you have an idea about.
Also add a new wound, such as Hypothermia, for swimming in winter.
EDIT:
Yeah it would require an empty inventory also, with the consequence that a couple of berry would make you drown .... probably, too convoluted for such small benefits.