5.8 miles, 1-3 hours
The Perimeter Road provides access to pretty much everything else one can see and do on the island! It's got fantastic views around the bay, it's a fun walk and a pretty good bike ride.
When taking a ferry, all walks start at Alaya Cove (formerly Hospital Cove). Pick up a map while there. The Cove also houses segway and bike rentals, a small store and restaurant, the Park Museum, the bus tour, and picnic grounds. Do check out the Museum for the interpretive exhibits, history, and island overview.
Follow the paved road up the hill past the Museum. One can continue up the paved road or take a switchback trail with lesser grade. Either way, both meet at the same intersection with the Perimeter Road. This description will continue clockwise around the island.
Watch the ferry schedule and keep track of the time. It's easy to find yourself racing to catch the last ferries back to shore.