Kalmus Beach at the end of Ocean Street in Hyannis is considered by some to offer the best windsurfing on the Cape in the spring, summer and fall. The steady breezes, warm waters and consistent waves off Nantucket Sound draw windsurfers from all over. Kalmus is one of the quieter and nicer public beaches on this part of the Cape.  Lots of smooth sand and the water has a nice easy drop off so it's a good beach for kids