Recently my hands have started getting prune after a short time in contact with water (I don’t know why). This was them after a water event at my summer camp. It was so bad that the top of my hand was pruned too, and the skin would peeling off if you scratched it.

This is false I'm pretty sure. The reason things prune and shrivel when In water is because normally in capillaries of tissue beds there is a balance between oncotic pressure in your capillaries, hydrostatic pressure in your capillaries and hydrostatic pressure in your extra cellular space. So in water there is more pressure in the extra cellular space driving water more into your blood vessels then under normal conditions shifting the equilibrium to a position where your tissues become a bit dehydrated because the balance between your cells and the extracellular space has to also shift. This is also the same reason you have to pee when in water because you have more blood in your circulatory system and therefore a higher glomerular filtration rate in your kidneys.

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