Cracks in an important Coromandel route have developed into a colossal landslide that left a minister gobsmacked – and the earth is still moving.

Emergency Management Minister Kieran McAnulty was in the Coromandel on Thursday to survey recent storm damage and says 'you had to see [SH25A] to believe it”.

'We saw the pictures and we knew it was a big deal, but for that to double in size in one day and for it still to be moving - we're talking about an event which is going to cause massive disruption to this region. It's going to take a long time to fix, and we won't know how long until the earth stops moving.”

After visiting SH25A, Kieran McAnulty says he couldn't believe what he'd seen and that it's 'extraordinary" how much the slip has grown.

But the site is still moving and, until the land is stable enough, contractors and engineers can only wait.

McAnulty has no estimate of the cost to repair, but he's looking to work with other ministers and the local civil defence to find solutions.

"It is very clear that the Coromandel is in a touch-and-go situation here, we've got isolated communities, we've got roads simply aren't passable at the moment,” says McAnulty.

SH25A has been plagued since mid-January, when cracks appeared and it was temporarily closed, then reopened under stop-go management.

It was closed again on Friday, when Waka Kotahi advised heavy rain was 'causing further instability” at the summit.

The existing cracks soon widened and a 'significant collapse” followed, with Coromandel MP Scott Simpson warning it could be unusable 'for months”.

"The Coromandel is in a touch-and-go situation,” Emergency Management Minister Kieran McAnulty said during a visit on Thursday. Photo: Mark Taylor/Stuff.

Waka Kotahi NZ Transport Agency has begun to assess the damage from a distance, and regional relationships director David Speirs says it has been a 'trying time”.

Once they can safely access the area, they will start a geotechnical investigation to determine the the best long-term fix for the site.

”It will be a very large job to restore the road... We don't know how long at this stage, the site is still quite dynamic,” says Speirs.

They are conscious of the pressing urgency to gain access again to what was described as a 'lifeline” route for those in the region but asked for leniency towards their staff.

-Te Aorewa Rolleston/Stuff.