When you sit or stay in water too long the skin starts absorbing that water and then your skin starts wrinkling.
Skin experts have said that when you sit in water too long your skin can literally fall off.
Well you're not gonna lose all your skin but your skin can start peeling off however new skin will grow in it's place.
But if you notice your skin is getting wrinkly when sitting in the tub too long then it's time to get out of the tub.
Your skin can become damaged eventually when you stay in the bathtub water or even stay in a swimming pool too long.
The same is true with a hot tub but in a hot tub the skin wrinkling is not your only problem as you can can become overheated when staying in a hot tub too long and suffer from heat stroke.