Folding kayak.
This folding kayak is made from the same material as those corrugated plastic political signs.
They stamp out a sheet into a special shape.
Crease folds into it like origami, and add some hardware and fittings. So it looks like this when you start to fold it into a kayak.
It folds into a kayak shape and a few buckles and gaskets hold it together watertight, which is easy because the panel edges are all above the waterline and only the folds are below the waterline. It's quite rigid.
Folds up into a lightweight 25 pound package you can put in the trunk of your car.