In 1930 two novice paddlers—Eric Sevareid and Walter C. Port—launched a secondhand 18-foot canvas canoe into the Minnesota River at Fort Snelling for an ambitious summer-long journey from Minneapolis to Hudson Bay. Without benefit of radio, motor, or good maps, the teenagers made their way over 2,250 miles of rivers, lakes, and difficult portages. Nearly four months later, after shooting hundreds of sets of rapids and surviving exceedingly bad conditions and even worse...