Close to 50 long-finned pilot whales are stranded on a remote beach at the top of the South Island.
The Department of Conservation (DoC) was first alerted to the mass stranding at the base of Farewell Spit in Golden Bay by a tour operator at 9.30 today.
A spokesperson said nine of the 49 whales have died.
DoC is aiming to refloat the whales once the water is deep enough and rangers are on site to assist them. High tide is about 7pm.
"Project Jonah marine mammal medics will assist with refloating the whales and caring for them on the beach, keeping them cool and wet until they can be refloated," DoC said.
"We have about 65 people assisting with the stranded whales currently. More people aren't needed at this time."
Project Jonah confirmed beaches would be checked for other whales that might have stranded further along the coast.
The last mass pilot whale stranding on Farewell Spit was in February 2017 when an estimated 600-700 whales were beached.
About 250 died while the rest were refloated.