Greenstone Ridge Trail

Greenstone Ridge Trail is Isle Royale's named, one-way backcountry traverse. The mapped route is about 40.0 miles from the Greenstone junction near Windigo to Hidden Lake on the island's east end, crossing the wooded ridge instead of looping back. The National Park Service describes the full backpacking itinerary as over 40 miles; campground approaches and the extra walk toward Lookout Louise explain why published totals differ. This is a multi-day trip, not a day hike: allow roughly 40 hours of walking before camp setup, rest days or boat schedules. Plan the exit first. Windigo has island transport, while Hidden Lake is boat-access only, so these endpoints do not connect by road.

Heading east from Windigo, the route reaches Island Mine, crosses the high ridge by Mount Desor and South Desor, passes the Ishpeming Tower and the Hatchet and Chickenbone lake country, then continues by Ojibway Tower and Mount Franklin toward Hidden Lake. Use the park's campground map to divide those legs into days that fit your pace and water plan; the ridge's long sections are tiring even without a heavy pack. Backcountry camping requires a permit, and groups of seven or more need advance reservations. Arrange island arrival and departure separately, and confirm boat connections before committing to a point-to-point itinerary.

The trail alternates between dense forest, more open ridge stretches and occasional views over the island's interior wetlands and Lake Superior. Ojibway Tower is a memorable viewpoint along the eastern half; the route also passes the old Ishpeming fire tower. Mount Desor is Isle Royale's highest point, but its wooded summit can be hard to pick out and does not open into a broad summit panorama. The route's appeal is the changing island landscape and long-distance crossing, with viewpoints appearing between stretches under trees rather than continuously.

The Lookout Louise–Mount Franklin section is a distinct, roughly five-mile one-way leg at the northeast end. The trail there is rocky and rooted, and the Park Service warns that navigation can be difficult on this less-traveled stretch. Lookout Louise itself is reached by a further one-mile walk from the Hidden Lake access. That makes a shorter visit possible, but even this option needs a boat to Hidden Lake and careful return planning; it is not a roadside day hike. Carry a detailed map and compass and know how to use both.

Potable water is limited to developed areas such as Windigo and Rock Harbor; expect to treat water gathered from interior sources and do not count on a ridge tap. The park recommends carrying at least two quarts per person and refilling when safe sources are available. Rooted, rocky footing and stretches that are hard to follow make slow progress likely, especially when brush hides the tread. Mosquitoes and black flies are most persistent in early summer and can linger into August. Pets are prohibited on Isle Royale trails.

If you want a section instead of the crossing, the Lookout Louise–Mount Franklin leg is about five miles one way, with the separate one-mile walk between Hidden Lake and Lookout Louise. You still need boat access and a plan to return to the landing. For a different partial itinerary, the park's section map helps match campgrounds, route length and available transport without treating the whole ridge as a loop.