A long day swimming at a pool or the beach typically wraps up with a hungry belly, hopefully sunburn-free skin, and wrinkly fingers. It turns out that like our fingerprints, those wrinkly patterns that form after our hands are in water for extended periods of time are also consistent. They remain the same even after multiple submersions in water, according to a study published in the May 2025 issues of the Journal of the Mechanical Behavior of Biomedical Materials. The skin on the palms of our hands and soles of our feet–or glabrous skin–is hairless and plays a role in sensing our environment. Glabrous skin has tons of receptors that send signals from our skin as electrical impulses that our brain can read. It is also the skin that wrinkles when exposed to water for a long time. The blood vessels beneath the skin contract, creating the wrinkles.