Heat the lemon juice in a sauce pan over medium-low heat. Add the honey and stir to dissolve.

Put watermelon and lemon juice in a blender; liquefy.

Pour watermelon mixture into a square 8x8 metal or glass baking dish, or into a bread loaf pan. Cover with plastic wrap and freeze until solid, about 4 hours.

10 to 15 minutes before serving time, remove the watermelon ice from the freezer to let it soften. Scoop and serve!