Just been writing some resources for the GA's website on the forthcoming PLASTIKI expedition.
The GA will be involved in tracking and reporting on the voyage and providing some curriculum materials for using the voyage in the classroom by UK geography teachers.
The PLASTIKI is a vessel made from recycled plastic bottles. It will set sail from San Francisco in 17 days and counting (there is a countdown on the main website page linked to from above) and visit various locations reporting back on major environmental themes.
It will complement the current voyage of the BBC Box, which is another useful maritime example. The Box is currently in the Indian Ocean.