This car-less Victorian town accessible via ferry is definitely a step back in time. At under 4 square miles, it is both easy to explore the entire island and find areas outside of the main downtown very much isolated. Circling the island is an 8-mile trail that is popular with bikers, and there are plenty of bike rental places on the island. There are some truly steep hills climbing up to Fort Mackinac, circa 1780, and even higher up to Fort Holmes, an 1814 fort that has been rebuilt. We explored both the trail along the circumference as well as very isolated inland trails.
Fun-fact: Mackinac is pronounced "Mackinaw".