Like in a long bath or going swimming for a while.

Answer:
Your skin is made up of two layers. The outer layer is called the epidermis and the lower level is the dermis. The outer layer (epidermis) produces an oily substance called sebum. You can see this substance when you touch a window or mirror and your “oily” fingerprint is left there. One job sebum does is it keeps water out of your skin—a job that it does very well. However, after long periods of time in a swimming pool, shower, or bathtub, much of the sebum is washed off and your outer layer of skin starts to absorb water. As it absorbs water it swells, but since the epidermis is “tied” down to your dermis in certain spots, it expands more where it isn’t “tied” down and this causes your skin to wrinkle. The difference between your skin and a raisin is that raisins wrinkle because they shrink, but your skin wrinkles because it is getting more massive.
Answer:
uh thats because the water seeps down into you skin and it wrinkles up!!