A stranded whale is checked over.

A stranded whale is checked over.
Wildlife authorities have said it's unclear what caused twenty-eight whales to become stranded at a remote beach in Far East Gippsland.

The mass beaching at the Croajingolong National Park between Petrel Point and Rame Head was first spotted by aircraft pilot Grant Shorland senior yesterday about 4pm.

Three wildlife experts that were flown in by helicopter found one dead humpback whale and 23 dead pilot whales.

Four of the pilot whales were earlier in a critical condition, but died this afternoon; two were euthanised, while the remaining two died of natural causes.

Pilot Grant Shorland said he was shocked and saddened by the mass stranding, which is the state's worst in more than 30 years.

"I've never seen whales like that before. We see a lot of other stuff on the beach, but not a big pod of whales like that."

The cause of the beaching remains unclear, but marine mammal expert Dr Kate Charlton-Robb said seismic activity of illness may have been a factor.

Incident Controller with the Department of Environment, Land, Water and Planning (DELWP), Michael Turner, earlier told 9News.com.au this morning he'd never seen a beaching of this scale in 32 years with the department.

"The whales are in a very remote part of the national park that's only really accessible on foot," Mr Turne said.

"I recently responded to a beaching in Point Hicks, but that was only one whale.

"We encourage people to steer clear of the area for safety reasons and to ensure the efforts of crews are not impacted," he said.

Sharks may be more active in the area.

Wildlife officers will remain in the area over the coming days, and will take samples for research to better understand why they beached themselves and how it can be prevented in the future.

The mass beaching comes just days after two massive pods of up to 145 pilot whales washed ashore on a beach in southern New Zealand.

Many died before help arrived, while the rest were euthanised by conservation workers.

New Zealand's Department of Conservation has released heartbreaking footage showing dozens of pilot whales sprawled helplessly in Mason Bay on the west coast of Stewart Island.