<p>Science magazine describes the Pascagoula River of southeast Mississippi as the last unaltered large river system in the lower 48 states and southern Canada. Along its banks and watershed 600,000 acres of public lands--wildlife management areas, national forest, wilderness areas, national wildlife refuges, Nature Conservancy preserves--ensure the creation of a tremendous natural river system. <p> To explore this sanctum, authors Ernest Herndon and Scott B. Williams traveled its entire 200-plus mile length by canoe and sea kayak, respectively. Each floated one of two major tributaries, Herndon taking the Leaf, Williams the Chickasawhay. They then met on the main Pascagoula and continued on to the Gulf Coast. Along the way the two saw alligators and ospreys, conservationists and good ole boys. They ran rapids and explored swamps, dodged logjams and investigated possible pollution sources. <p> Herndon and Williams brought considerable skills and experience to their journey. Herndon has gone on backcountry trips to places as far-flung as Papua New Guinea and Alaska, while Williams paddled his sea kayak solo down the Mississippi and across the Caribbean. Together they've canoed and kayaked all over the South as well as in remote parts of Central America. Both agree the Pascagoula basin is one of the most intriguing outdoor destinations they have experienced. <p> The book gives the armchair explorer a vivid feeling of what it would be like to float this wonderful river and provides a wealth of information about what makes it special and the problems that threaten it. <p>Ernest HerndonÊis a staff writer for the <i>Enterprise-Journal</i> in McComb, Mississippi, and is the author of several books. See the author's Web site at . Scott B. Williams is a woodworker, boat carpenter, and freelance writer based in Jackson, Mississippi. See the author's website at .