It was something I always had wanted to do—go under my own power down a river to the sea. At its core was both the idea and the sensation of freedom. Living in a world so thoroughly carved up and sold off, there were only two ways I had discovered to really experience freedom in nature the way it once must have been everywhere. One way was hiking through a national forest. The other was traveling on a river, which, although usually flanked by private property, nevertheless was itself considered public, and by Texas law one was allowed to camp along its banks when en route. I had thought first of a canoe trip, perhaps floating down the Colorado from Austin to the Gulf of…