It's the last day to suggest a name for the new Auckland City Rail Link tunnel boring machine.

It will be named after one of the country's number of inspiring women.

'Subterranean Sue' after Dame Susan Devoy and 'Jacindigger' after Prime Minister Jacinda Ardern are among suggestions so far.

Anyone in New Zealand over five years old can make a suggestion.

The top three will be selected by a panel before going to New Zealanders for a vote.

"All those who have been nominated share one thing in common - their inspiring talents, skills and leadership have made, or are making, a huge impact on New Zealand," City Rail Link chief executive Sean Sweeney said in February.

"The [boring machine] will have a very forceful influence on the project, and that's why we want the name of a woman who has had an equally strong influence on our country."