You wouldn't soak up water indefinitely because skin is held on by connective tissue - hence wrinkling, which is when the skin in between soaks up water but the connective tissue doesn't. However, your skin is now very soft and easily damaged, and where there is damage, there is the possibility of infection... Assuming you could get round the skin problems, your joints would seize up through being in one position - so let's relocate to the swimming pool. Ah, but water is a very powerful absorber of heat, so you're getting hyporthermic. Let's heat up the pool. That's more comfortable - but now it's dropping your blood pressure as your skin capillaries dilate to get rid of the excess heat, plus it's increasing your metabolic rate and kidney function, so whatever thingy you've got for dealing with pee is working overtime. Net result is after quite a short time you're dehydrated, feeling a bit light headed and very, very tired.
Hydrotherapy pools are generally around blood heat, and recommendations for staff to stay in the pool are around 3 hours a day. Much more than that and the fatigue sets in.