A watermelon is a type of edible fruit. They are 92% water. About six percent of a watermelon is sugar. This makes them very sweet. There are many different types of watermelon. Some have a green rind on the outside and a red-pink flesh on the inside, with black seeds. Some can have yellow flesh, and some can be seedless. The green rind on the outside is not usually eaten, though it can be used as a vegetable. It can also be stewed or pickled. Most watermelons are oblong or spherical. In Japan, watermelons are grown in different shapes. Many people like to eat watermelon in the summer because the fruit is cool and refreshing.