Immersion foot

Trench foot

Immersion foot syndromes are a class of foot injury caused by water absorption in the outer layer of skin. There are different subclass names for this condition based on the temperature of the water to which the foot is exposed. These include trench foot, tropical immersion foot, and warm water immersion foot.: 26–7  In one 3-day military study, it was found that submersion in water allowing for a higher skin temperature resulted in worse skin maceration and pain.

Source: Wikipedia

Trench foot is a form of incipient gangrene in which the foot turns mottled and blistered. In severe cases toes would be lost. The name comes from the time of the First World War. Soldiers in the trenches had feet perpetually damp and cold. This coupled with tight puttees, which dangerously reduced blood circulation below the ankle, meant that their feet were starved of blood.
(G) Very specific problems