Cotton mouth
From Openwaterpedia
noun - Cotton mouth (or dry mouth) is oral distress due to swimming long periods in salt water when the mouth gets very dry, the lips and corners of the mouth crack and become sore, the tongue swells and becomes sore, taste is vastly altered, the mouth feels like it is burning or tingling, the throat becomes irritated, and/or swallowing becomes very difficult. Over long periods, it can also become difficult to talk normally and the mouth feels 'dry' even while swimming.
Synonyms
dry mouth, xerostomia (from the Greek words ξηρός (xeros) meaning "dry" and στόμα (stoma) meaning "mouth")