DAVID DE ROTHSCHILD'S PLAN for cleaning garbage out of the ocean starts with a boat made of trash. By July, the 30-year-old British explorer and six crewmates will set sail from San Francisco to Sydney, Australia, aboard the Plastiki, a high-tech 60-foot catamaran and marine-research platform with hulls made from discarded soda bottles. "The plan is to showcase a smart solution to waste," says de Rothschild. The awareness-raising expedition, inspired by Thor Heyerdahl's famed 1947 journey from Peru to Fiji on the balsa raft Kon-Tiki, was conceived after de Rothschild read a 2006 United Nations study estimating that 46,000 pieces of plastic are floating on every square mile of ocean. When he reaches Sydney, de Rothschild plans to recycle the vessel. "Should we up-cycle it into clothing or carpets?" he says. "We're going to let our online community decide." How about recycling it into …a sailboat?

1. Solar panels, turbines, and a stationary bike generate ELECTRICITY that's stored in banks of 12-volt batteries—enough to run the ship's LED lights and electrical equipment and to power its auxiliary motor for two hours.

2. The waste system extracts nitrogen from urine and composts SOLID WASTE with kitchen scraps (the toilet has a grinder) and earthworms to make fertilizer that will be offloaded at port calls.

3. Each HULL is composed of 7,500 used two-liter bottles held together by a plastic frame. The bottles are pressurized with CO₂ to improve hull rigidity.

4. The hand-operated WATER DESALINATOR creates a vacuum to extract the salt from seawater and can produce six liters at a time.