A few years ago ReMain, a local non-profit, designed a phone app for self-guided exploration and touring by bicycle called trACK Nantucket. The idea was to create an alternative to car use and enable folks to see some of the places on-island that they might normally not be able to.
From Remain’s web site: “We are committed to helping people on Nantucket get around the Island in environmentally responsible ways that respect the inherent beauty and natural environment of this place and promote a healthier lifestyle.”