Aucklanders are being encouraged to leave the car at home tomorrow, with most public transport free for the day.
All buses, trains, and some ferry services will be free as Auckland Transport celebrates 100 million passenger trips in the past year.
Extra staff and buses are being put on to cope with demand.
Auckland Transport chief executive Shane Ellison said it was a great opportunity for all Aucklanders to try public transport.
Fullers360 is offering free ferries between Devonport and Auckland and free buses on Waiheke Island.
People with multi-ride passes will be able to travel free on the ferry between Waiheke and Auckland tomorrow.
Free services will not include the Skybus to the airport, or ferry services to and from Rangitoto, Tiritiri Matangi or Mototapu islands.