The Opoutere beach whale deaths came within days of two mass strandings in Tasmanian waters, including the stranded pod (pictured) on King Island. Picture / Reuters

The Opoutere beach whale deaths came within days of two mass strandings in Tasmanian waters, including the stranded pod (pictured) on King Island. Picture / Reuters

More than 50 dead whales will be buried today after a mass stranding at a Coromandel beach.

Seventy-three pilot whales came ashore at Opoutere beach on Sunday night. By late last night, only 21 were alive. Eleven of those had been refloated but little hope was held of saving the remaining 10.

A local resident discovered the stranded whales at the north end of the 4.5km beach about 10am yesterday and immediately alerted the Department of Conservation.

Twenty DoC staff raced to the beach, where 50 volunteers helped them to try to refloat the whales, which ranged in size from 4m to 6m.

DoC Hauraki area manager John Gaukrodger said the rescue effort was hampered by the fact the whales had been out of the water for hours.

The stranding was not noticed earlier because several hundred metres of dunes separate the beach from houses.

He said late last night the 10 remaining whales had been out of the water for close to 24 hours. "It could be a bit much to expect they will be salvaged."

A digger was used to help to channel water around the whales.

It also dug a channel to float them out to sea.

Today, the machine would dig graves for the whales that did not survive.

"With that number, we'll be burying them right on site," Mr Gaukrodger said.

Mr Gaukrodger said the stranding had been an emotional ordeal for some of the volunteers, who included members of local iwi, residents and members of Project Jonah, who are trained in whale rescues.

It was the biggest whale stranding in the area in over a decade. Most strandings in the Coromandel have involved individual whales.

Mass strandings round the New Zealand coast are not uncommon, though the reasons remain unclear.

Whale experts say sometimes a herd may follow a sick leader or a young whale may strand by accident and the rest try to rescue it.

Mr Gaukrodger could not say whether the whales that were successfully refloated were out of danger.

They were moved into the seabound channel with flotation equipment. The main task before they could be moved was to keep them wet.

The DOC staff and volunteers covered the whales in water throughout the day.