Make a backyard bowling alley. Add food coloring to clear plastic bottles of water. Use party streamers as lane margins. Add glow sticks for night bowling. (These would make great outdoor table nightlights also with the glowsticks, gonna try it!
Make glowing water WITHOUT highlighters! This new recipe from Growing A Jeweled Rose is a great alternative as it is made from kid safe materials (non-toxic fluorescent paint) with a RAINBOW of waters to add to your play!