Use a knife and cutting board to cut the watermelon into manageable chunks, removing seeds as needed. Measure out approximately 3 cups of cubed flesh.
Add the watermelon cubes and ice cubes into the blender. Pour in 1-2 tablespoons of honey or agave syrup, and add lime juice if desired.
Secure the lid on the blender and blend on high speed until the mixture is smooth, bright red, and frothy, about 30-45 seconds. Stop occasionally to scrape down the sides if needed.
Pour the smoothie into glasses, observing the vibrant red color and velvety texture. Serve immediately for the best freshness.
Optional: garnish with a small wedge of lime or a sprig of mint for presentation. Enjoy your refreshing watermelon smoothie.
