I didn't know what a tule canoe was, or even what tules were, so I had a peek at the link.
"Tules are tall marshland reeds; they’re fat and spongy. Cut one open and you’ll see the network of air pockets that offer excellent flotation and workable structure. When bundled together tightly with rope, they may be molded into a beautiful and functional boat. At a recent gathering at Caldwell Lake, in Valyermo, CA, Jim Robertson leading 12 students did just that."