The St. John, wilder and less accessible than its better-known cousin, the Allagash, is navigable only during the May melts. Drive the four hours from Bangor to Baker Lake and launch your canoe down the 100-mile ribbon of glossy straightaways and mellow Class IIs. The river cuts through the deep northern woods near the Canadian frontier, where the only traces of civilization are a few ghost logging camps. Easy paddling days mean pulling into camp early for afternoons of catching brook trout. Canoe Maine does a six-day trip ($750 per person; canoemaine.com).