I hate to contradict Skipper Bob, but I think the mileage from Port Severn to Sault Ste Marie is closer to 400 miles (plus or minus) depending whether you stay in the small craft channel of Georgian Bay or go right across the center. According to the mileage listed in the appendix of our book for the route we took (and we didn't go as far north as Sault Ste. Marie), I estimate it to be 350 to 400 miles minimum. Eva & Ron Stob, Directors America's Great Loop Cruisers' Association P. O. Box 168, Greenback, TN 37742 865-856-7888 Fax: 865-856-7889 Website: www.greatloop.com