Weather: Ferocious waves smash sea wall blocks across Kaikoura highway

Massive seas have smashed into the Kaikoura coast overnight on Sunday, destroying the sea wall and pushing temporary blocks onto State Highway 1.

Images from Sunday night show the giant blocks being buffeted by the swells, which sweep over the road.

Photos of the aftermath show them strewn across the highway - some pushed across both lanes after being wrenched from their positions.

Images show the giant blocks wrenched from their positions.
Images show the giant blocks wrenched from their positions. Photo credit: Supplied / NZTA

The New Zealand Transport Agency warns the damage will lead to delays for motorists - and another high tide is heading in later this morning.

"Southbound traffic from Blenheim should use the alternate route - SH63, SH6, SH65, SH7 and back onto SH1 at Waipara," a spokesperson says.

It's not the first wave damage caused by the recent bad weather. In Wellington, large waves broke along the Eastbourne coastline causing trouble for some motorists and leaving debris thrown onto the road.

Two Interislander ferries were cancelled after huge waves were recorded in the Cook Strait.

And the Firth of Thames is bearing the storm's battle scars with the coastline now unrecognisable after chunks of the Thames Coast Road were swept away between Tararu and Manaia on Friday.

The damaged sections of the road could be shut for weeks, and roading contractors are now assessing the damage.

Mayor John Tregidga says the whole coastline has completely changed with large rocks dumped on the road and silt up to half a metre deep.

"You wouldn't recognise it... the damage is so significant," he says.

"For someone that's been in this game 30 years, I haven't seen this sort of damage since the 1981 floods that we had."