Why do your fingers look like prunes after swimming for a long time?

Fingers look like Prunes after prolonged exposure to water due to a natural physiological response called vasoconstriction. When submerged in water, the body responds by narrowing blood vessels in the fingers, causing the skin to wrinkle. This wrinkling is believed to enhance grip on wet surfaces, providing an evolutionary advantage. The effect is temporary and reverses once the fingers dry out and blood flow returns to normal.