And how will you be getting to the island?

Is this about driving to an island? If you need a plane or boat to the island and still call that trip "walking", then someone can take a plane or boat to the island and rent a car and call it "driving" or "driving plus walking".

Or if you're just saying that a very good backpacker that happens to be in greenland can get more places by walking because of a lack of roads, that might be true. But for a normal person in a typical household, their walking range is not that big. If you're in the US or Europe the roads reach almost everywhere.