Lake Superior's notoriously fickle weather, plus a few centuries' worth of shoddy navigation, have turned Thunder Bay into a graveyard for schooners, yachts, and even a Confederate blockade runner. As a result, it's a diver's paradise. Wally Peterson, owner of Wally's Thunder Country Diving (thundercountrydiving.com), has been diving here since 1976 and can serve up coordinates for everything from shallow wood wrecks for intermediate divers to deep, technical dives like the Gunilda, a yacht that sank three miles offshore in 1911 and is still remarkably well preserved. (Thirty-eight-degree water can embalm anything.) Peterson offers diving-certification lessons and guided day trips on Superior (lesson, US$340; trips from US$90). Crash at the Dockside Bed and Breakfast, a restored 38-foot Downeaster docked in Thunder Bay Marine Park (doubles, US$118; sailsuperior.com). Ask nicely and captain Gregory Heroux will take the inn for an evening sail.