One of two humpback whales stranded on a Northland beach has died.

It is understood the dead whale is a calf.

"Sadly the smaller of the two whales had died and Iwi have blessed," Project Jonah posted this morning.

"The rescue effort for the remaining whale has ramped up with channels being dug."

Rescuers trying to free the stranded humpbacks resumed work this morning, with the aim of turning the mammals and digging a trench in their bid to set them free.

The two whales, who Department of Conservation believe to be a mother and calf, were first spotted stuck on Piriro Beach, 2km south of Baylys Beach, Northland.

DoC Kauri Coast operations manager Stephen Soole said they have organised heavy machinery to help dig the trench and turn the whales who were first spotted on the beach about 7am yesterday.

A huge response from the community and Project Jonah volunteers then saw up to 200 people help the whales.

A group of volunteers remained with the mammals on the beach overnight, he said.

Soole said they had already resumed their efforts this morning with the tide currently going out.

"The next high tide is about 5pm so between now and then the plan is to dig a channel in deep water, while the tide allows, with heavy machinery and to get some deeper water under the whales and position them, because they're side on at the moment, so turn them around facing out to sea so when the tide does come in we will attempt to refloat."

He said while whale strandings weren't unusual it was unusual to see mother and calf whales stranded on Piriro Beach.

He was grateful for the community's efforts yesterday and despite expecting a lower number of helpers today, they were still hopeful of a successful refloat.

"We had a tremendous number of volunteers yesterday, between 100 and 200 people on the beach helping out.

"Today being a weekday there will be less, but we've got a number of volunteers out there and have Project Jonah helping out as well so its pretty much under control out there."

DoC Kauri Coast ranger Manu Kareko earlier told the Northern Advocate that being involved in the rescue was a humbling experience.

"It makes you feel pretty insignificant, standing next to something this big. I've only ever been involved in one other situation like this and it was to try and remove two pygmy sperm whales, which were already deceased.

"These whales though, they're alive and they're just really massive."