Nantucket is up front about it. Bring your bike on the ferry but leave your car on the mainland. Two main ferry services leave from Hyannis. There are seasonal ones from Martha's Vineyard and Harwich. There are high speed ferries and one carrying cars. Nantucket Memorial Airport has flights incoming from Hyannis, Martha's Vineyard, Boston, New Bedford, Providence, La Guardia, White Plains, NY, Newark, Philadelphia, Baltimore and Washington DC. Private planes can be accommodated as well. Once on Nantucket, there are several ways to get around without a car: by bicycle, on foot, shuttle busses in season and taxis. Off-season, it may be more practical to rent a car.