Why do your fingertips go crinkly when you have been in water for a long time?

Question

Why do your fingertips go crinkly when you have been in water for a long time?

Answer 1

your skin is a semi permeable membrane. This means that through osmosis water can enter through your skin.

Your skin is usually covered in a layer of oil that will stop water entering your skin, but when you wash using soap you remove this layer and therefore water enters you fingers and swells them slightly