Currently 12,000 to 16,000 2-litre soda bottles are being collected to fill in the twin hulls of their Plastiki vessel. Each bottle with be pressurised using dry ice powder that will sublimate into carbon dioxide gas. If all goes as planned, the vessel will carry four crewmembers on a 17,700km journey starting this April from San Francisco to Sydney only to be broken down and recycled at the end of the trip. Apparently, only the masts of the ship are metal, leaving the remaining 90% as recycled material.
Sure it's dangerous, but the design is obviously more professional (and less risky) than the paper bottle boat that his 22-year old predecessor cobbled together with his father. My guess is that the outcome will be much better this time around. [CNN and Architecture for Humanity]