Isle Royale National Park is a U.S. National Park in the state of Michigan. Isle Royale, the largest island in Lake Superior, is over 45 miles (72 km) in length and 9 miles (14 km) wide at its widest point. The park is made of Isle Royale itself and multiple smaller islands, along with any submerged lands within 4.5 miles (7.24 km) of the surrounding islands (16USC408g). Isle Royale National Park was established on April 3, 1940, was designated as a Wilderness Area in 1976, and was made an International Biosphere Reserve in 1980. It is a relatively small national park at 894 square miles (2,314 km²), with only 209 square miles (542 km²) above water. At the U.S.-Canada border, it will meet the borders of the future Canadian Lake Superior National Marine Conservation Area.
The Greenstone Ridge is a high ridge in the center of the island and carries the longest trail in the park, the Greenstone Ridge trail, which runs 40 miles (60 km) from one end of the island to the other. This is generally done as a 4 or 5 day hike. A boat shuttle can carry hikers back to their starting port. In total there are 165 miles (265 km) of hiking trails. There are also canoe/kayak routes, many involving portages, along coastal bays and inland lakes.
Sleeping accommodations at the park are limited to the lodge at Rock Harbor and 36 designated wilderness campgrounds. Some campgrounds are accessible only by private boat; others in the interior are accessible only by trail or by canoe/kayak on the island lakes. The campsites vary in capacity but typically include a few three-sided wood shelters (the fourth wall is screened) with floors and roofs, and several individual sites suitable for pitching a small tent. Some tent sites with space for groups of up to 10 are available, and are used for overflow if all the individual sites are filled. The only amenities at the campgrounds are pit toilets, picnic tables, and fire-rings at specific areas. Campfires are not permitted at most campgrounds; gas or alcohol camp stoves are recommended. Drinking and cooking water must be drawn from local water sources (Lake Superior and inland lakes) and filtered, treated, or boiled to avoid parasites. Hunting is not permitted, but fishing is, and edible berries (blueberries, thimbleberries) may be picked from the trail.
Bedrock on Isle Royale is basalt or sandstone and conglomerates on the 1100 million year old Midcontinent Rift. Most of the island is covered with a thin layer of glacial material. A number of small native copper mines were active in the 1800s but mining was never really prosperous. Recent analyses by the USGS of both unmineralized basalt and copper-mineralized rock show that a small amount of naturally-occurring mercury is associated with mineralization.
The park is accessible by floatplane and by ferry during the summer months from Grand Portage, Minnesota, and from Houghton and Copper Harbor in Michigan. Private boats travel to the island mainly from Thunder Bay, Ontario, the closest city to the park.
Isle Royale is not popular with day-trippers because of the scheduling constraints of transportation to and from the park. The ferries that make this voyage have a relatively long transit time, and thus spend only short periods on the island. Some ferries may delay—and in some situations cancel—trips during heavy weather.
The Ranger III is a 165-foot (50 m) ship operated by the National Park Service, said to be the largest piece of equipment in the National Park system. It carries 125 passengers, canoes and kayaks -- even small powerboats -- and operates out of Houghton, Michigan. This is a six-hour voyage from the park, and the ship overnights at the island before returning the next day, making two round trips each week, June to mid-September. The Isle Royale Queen out of Copper Harbor, Michigan, and the Wenonah, out of Grand Portage, Minnesota, operate round-trips daily in peak season, less frequently in early summer and autumn. The Voyageur II, also out of Grand Portage, crosses up to three times a week, overnighting at Rock Harbor and providing transportation between popular lakeside campgrounds. The Voyageur and boat taxi services ferry hikers to points along the island, allowing a one-way hike back to Rock Harbor or Windigo.
For the 2008 season, the Ranger III will carry visitors to/from Windigo on several occasions. This new schedule will allow visitors to park in Houghton, MI while traversing the entire length of the island. Visitors may land at Rock Harbor and depart from Windigo several days later or vice versa. Formerly, visitors would have paid an additional fare to ride the Voyageur II in one direction to do a cross-island hike.
Because of the difficulty of travel and the hazards of wilderness survival during the winter months, it is the only major National Park Service park to close entirely for the season. Because of the relative difficulty reaching the park and its seasonal closing, fewer than 20,000 people a year visit Isle Royale - fewer than the number of people who visit the most popular national parks in a single day.