Get ready to add an hour to your journey if you're going to Kaikoura today.

Travellers are being told to use the inland route while State Highway One between Hundalee and Kaikoura is closed.

It's because of crews clearing rock and debris.

Crews will be will clearing it by flushing the debris off hillsides with helicopters that have monsoon buckets.

The work is expected to be finished tomorrow.