Dagny at Wikimedia Commons, released into public domain.)It’s one thing to be appalled by the monstrous accumulation of millions of square miles of plastic waste spinning slowly in the North Pacific gyre. It’s another thing entirely to build an ocean-going vessel out of plastic waste and set out across the sea to call attention to the environmental catastrophe.

That’s exactly what two men, one from California and one from Hawaii, are now doing. The two — Marcus Eriksen, a Ph.D., Gulf War vet and director of research and education for the Long Beach-based Algalita Marine Research Foundation, and Joel Paschal, a former businessman in Hawaii and a one-time employee of the National Oceanic and Atmospheric Administration (NOAA) — are sailing across the Pacific in a homemade vessel, Kon Tiki-style, to “raise awareness about plastic fouling our oceans.”

And foul it is: the “garbage soup” swirling in the North Pacific gyre stretches across some five million square miles, an area twice as large as the continental U.S. Worse still, the floating dump is steadily growing and threatening every level of the food chain … yes, all the way up to humans.

The big chunks of plastic — bottles, six-pack rings, caps and more — entangle wildlife or choke creatures that swallow them. But the smaller bits — broken-down fragments and microscopic nurdles from plastics manufacturing — are ingested without immediate harm. It’s then that the longer-lasting damage begins: the tiny swallowed bits attract DDT, PCBs and other poisons, and gradually accumulate in the tissues of jellyfish, fish and other creatures. Sooner or later, people end up eating that poisoned plastic too.

It might be “out of sight” for most of us, but Eriksen and Paschal are determined to make it “out of mind” no longer. That’s why they’re sailing from Long Beach to Hawaii in an ocean-going junk made of actual junk: a discarded Cessna cockpit rigged with plastic waste to 15,000 plastic bottles. The vessel’s name? “Junk,” of course.

Throughout their journey, Eriksen and Paschal will be taking ocean surface samples, reporting on their findings and blogging about their experiences. Through the Algalita foundation, they’re also seeking sponsors for their message-in-a-bottle campaign. After they finish their voyage, they plan to take those messages on a tour of the West Coast before delivering them to state and local lawmakers.