Red light: The water is polluted! - Green light the water is safe!

Inventors Soo-in Yang and David Benjamin create an innovative pollution monitor that utilizes LED lights to denote polluted or "safe" areas for aquatic participation.

Though seemingly impractical since most people swim in the day and aquatic life could be attracted to the lights and possibly unsafe water, I think these lights are geared more to inspire a "call to action" rather than a useful way to protect us or the fish.

Found at Inhabitat