All transportation is on foot, by canoe or kayak, sailboat or by motorboat. Except for a few wide, flat trails at the ports for NPS equipment, and a little pavement in the Snug Harbor area, there are no roads on the island. Mountain bikes and wheeled portage devices are not permitted.
As a wilderness area, the park does not meet modern expectations of accessibility. You need to be able to walk on rough surfaces and steep terrain to get anywhere at all beyond the immediate vicinity of the ports. At Windigo, even the information office and store are up a short but steep hill. Wheelchairs are permitted but not actively accommodated; if you rely on one, you'll find ferry dis/embarking itself difficult, to say nothing of getting around. Lakeshore canoeing and sightseeing by boat are the best options for those with limited mobility. Service animals are permitted, but only with prior arrangements.
By Paddle
Several of the inland lakes and protected inlets of Lake Superior are connected by portages ranging from a few dozen feet to a few miles. Traveling by canoe or kayak obviously won't get you to all parts of the island not even the whole shoreline; the northwest coast is generally considered unsafe, with few places to beach, but it provides a different way of seeing the park, taking you to some parts the trails don't reach.
By "Taxi"
The Sandy, a "water taxi" operated by Rock Harbor Lodge & Marina, can take you to various places on the east end of the island. +1 906-337-4993 (http://rockharborlodge.com/) It's fairly costly, especially for small groups. For example, a one-way trip for one or two people to Daisy Farm campground 6 miles away costs $91; for a capacity party of six, the fare goes up to $110. There's only one Sandy and she also provides scheduled sightseeing tours, so reservations are recommended.
On foot
A 165-mile network of groomed trails connects most areas of the island. These are unpaved, and only somewhat improved, with exposed roots and stone common. When crossing "bald" areas of exposed solid rock, small cairns of stones are piled periodically to mark the route. In marshy areas, plank walkways have been built to allow passage and small bridges cross flowing streams.
By plane
If you simply must get from one end of the island to the other on a tight schedule, the floatplane service may be able to accommodate you, but advance notice and reservations are required, and the fare is a hefty $280 per person round trip; see "Get in".
By "Bus"
The island's "bus" is the Voyageur II. It's one of the ferries from Grand Portage see "Get in", but between crossings to/from the mainland, it circumnavigates the island, from Windigo to Snug Harbor along the north side one day, then back to Windigo along the south side the next, making it useful for getting from one part of the island to another. During the summer it makes three runs each week, fewer in early May or late September/October. In addition to the two main ports, it can do pick-ups and drop-offs at McCargoe Cove and Belle Isle north side, Mon/Wed/Sat, and Daisy Farm, Chippewa Harbor, and Malone Bay south side, Tue/Thu/Sun, with fares of $40-$52 per person. It stops at these intermediate docks only by request, and it doesn't swing by close enough to be flagged down, so book passage in advance. The Voyageur II allows hikers to thru-hike from Windigo to Rock Harbor or vice-versa, though a new 2008 service by the Ranger III failed and only using the VoyageurII can accomplish this.