Okay, we all do this so I wanted to know why.
Despite its appearance, your skin isn’t shriveling after your bath. Actually, it’s expanding.
The skin on the fingers, palms, toes and soles wrinkles only after it is saturated with water (a prolonged stay underwater in the swimming pool will create the same effect, or washing the dishes) The stratum corneum — the thick, dead, horny layer of the skin that protects us from the environment and that makes the skin on our hands and feet tougher and thicker than that on our stomachs and faces — expands when it soaks up water. This expansion causes the wrinkling effect.
So why doesn’t the skin on other parts of the body also wrinkle when saturated? Actually, it does but there is more room for the moisture to be absorbed in these less densely packed area before it will show.