A watermelon slice is a food item that can be obtained by using a knife on a watermelon. This will cut the watermelon into three slices (an unsliced watermelon cannot be eaten). The amount a watermelon slice heals is affected by your maximum hitpoints in the same way as a Saradomin brew. In watermelon slices' case, each slice heals 5% of the player's maximum hitpoints.
Composting watermelon slices will result in regular compost and NOT supercompost. Use whole watermelons instead.
Eating a watermelon slice will not yield any watermelon seeds.