When skin is kept cool and moist for a long time, rewarming causes a rush of blood to the heat-dilated vessels near the surface of a human body. The swollen vessels can't take the load. Fluid and metabolic waste products leak out of the vessels and into the surrounding tissue. Those tissues swell and itch, and hurt. Pus may fill the lesions in a severe case.
Treatment includes keeping the damaged skin warm and dry, and applying a protective ointment.
If the wet and cold are isolated in boots, another non-freezing problem, immersion foot, might develop. Owners of these feet complain of numbness, tingling pain, and itching. The feet look white or mottled in disgusting shades of blue, gray, and burgundy. On rewarming the pain does much more than tingle, and swelling and redness occur. Severe cases crack the skin and bacterial invasion is imminent.