Nantucket beach featuring swimming, windsurfing, sailing and kayaking lessons and equipment rentals.. In Short Offering the most services of any beach on the island, Jetties has umbrellas and chairs, windsurfing, sailboat and kayak equipment for rent. Lessons, as well as swimming instruction, make it popular with families. As with many of the beaches that face Nantucket Sound, it has more pebbles and shells than you'll find on the shores along the open ocean. In August, there's an annual contest--Sand Castle and Sculpture Day. For pre-registration call (508) 228-1700.