In a blender, put the watermelon chunks, squeeze in the lime juice and pour in the ginger ale. Blend until smooth.
Add 2 cups of ice (you might need more) and blend until smoothie consistency, or pretty much what you like.
Slice up some lime slices, cut into one edge and then secure on the edge of the glass. You can add paper umbrella’s like my daughter did if you’d like. Very summery, very refreshing!