Auckland buses, trains and some ferries to run for free on Sunday to celebrate 100m trips

Aucklanders will be able to travel for free on Sunday to mark 100 million passenger trips on public transport in the past 12 months, Auckland Transport has announced.

All buses, trains and some ferry services will be free for the Auckland public all day to celebrate the milestone.

"It's also a great opportunity for Aucklanders to try public transport services which have changed dramatically over the past decade," AT CEO Shane Ellison said in a statement.

Extra staff, including transport officers, will be available at key locations to ensure the public stays safe and gets where they need to go, group manager of metro services Stacey van der Putten said.

A bus driver at the wheel.