Watermelon is healthy in that it contains tremendous amounts of water, boosts the immune system, and provides essential carbohydrates for the brain.
It is possible to eat too much watermelon and suffer from those things too. Watermelons are said to be one of the healthiest fruits available because they are 90% water. This makes them perfect for hot days when a cool drink is needed, as well as those days when sports or exercise make you want to rehydrate (and replace necessary electrolytes).

One key advantage of eating enough fruit each day is that it can curb sugar cravings later on in the day or week...it gives your body what it needs instead of being left with nothing but highly caloric snack foods like chocolate bars.

Read more about the health benefits of watermelon here https://foodnutrition.site/is-watermelon-good-for-eyesight/