A rescue effort is underway after nearly a dozen dolphins beached in a mass stranding on Waiheke Island, with two stricken mammals already dead.

Project Jonah says it is currently coordinating with the Department of Conservation to tend to the stranded mammals.

There are currently around 10 dolphins stranded in Whakanewha Bay that locals are trying to save.

"We have local medics onsite and senior staff with equipment on the way," Project Jonah tweeted.

The Department of Conservation's Auckland Inner Islands operations manager Emma Kearney said staff from both organisations were either on the island or heading to it this afternoon to work on the rescue effort.

Buckets of water nearby a dolphin stranded at low tide. Photo / Prepper Kiwi

Local iwi Ngāti Pāoa were also at the scene supporting the rescue.

"The animals are common dolphins, and there are estimated to be 10, including one calf," said Kearney.

"Unfortunately, two animals have already died."

The next high tide at Whakanewha Bay is at about 7.26pm.

Project Jonah was expected to bring pontoons to help float the mammals to safety.

Pictures from the scene show stricken dolphins beached on a shallow bay at Whakanewha Regional Park on the southern coast of the island, near Auckland.

Scores of locals have turned out to help save the stricken mammals, some shown flailing helplessly on the wet sand.

A local livestreaming the rescue effort said there appeared to be a number of juvenile dolphins with their parents.

Locals can be seen dousing them in water and covering them in makeshift wet blankets using towels and large fern fronds.

A local vet was currently at the beach tending to the stranded mammals.