Aquarium's Sidewalk Ad Visible Only When It Rains

Here's an interesting bit of street advertising—an aquarium ad from Holland that appears on the sidewalk only when it rains. "Sea Life never lets you go" reads the ad, featuring an octopus, advertising the Sea Life aquarium in Scheveningen. The technology was designed by Fresh Green Ads, a "green media" agency that offers "a portfolio of sustainable media that create awareness and impact for your brands, with a minimal impact on the environment." There's no mention of how, exactly, the octopus appears when wet.