One of the best places to ride on Nantucket is Pocomo Point. It is accessible by car and offers a public launching point within the harbor that anyone can get to and works in a broad range of wind directions. When you come to the end of Pocomo Road, reach the parking lot, and walk down to the waterfront you will know why it is such an incredible spot.
Home to the best ocean side riding in New England, the southside of Nantucket can produce some incredible downwinders and breaking wave conditions. There are public access points throughout the south shore: Tom Nevers, Cisco, & Madaket are three great options. If you are going to ride the south side, be sure that you are a confident rider who can handle getting out past surf and other breaking waves.