Watermelon is about 92% water, and the other 8% does quiet work: potassium and magnesium, the same electrolytes sports drinks advertise, plus citrulline, an amino acid researchers have studied for blood flow and post-exercise soreness. One more detail worth knowing: watermelon is one of the better natural sources of lycopene, the red pigment associated in research with heart and skin health, and unlike tomatoes it needs no cooking to release it. A cold slice on an August afternoon is hydration with benefits. Full profile in the Nutrition Hub at dietdiscipline.com/nutrition-hub.