For many people, camping/emergency lanterns are one of those things that may sit for months without being used, only to have dead batteries when they're finally needed again. While solar-powered lanterns are one alternative, they do still need to sit in the sunlight for a few hours in order to charge. That's where Hydra-Light's PL-500 comes in. It's a fuel cell-powered lantern that's ready to shine as soon as it receives some salt water.