From:
Easy Underwater Viewer
Budding secret agents can investigate fishy activity in local ponds with a sneaky spying device.
1. Rinse out an empty half-gallon carton of milk; cut off top and bottom. Let dry.
2. Cover one end with plastic wrap, securing with a rubber band. Then submerge the wrapped end partially in water (an adult should supervise), and look through the top to see what's going on below.
