At least 90 whales have died and more feared to be dying after hundreds were left stranded off Tasmania in Australia.
However, rescuers were able to save 25 of the animals on Tuesday and are aiming to escort more back into the sea.
The pilot whales were discovered in shallow waters off the west coast of the island on Monday.
It’s unknown what drew the whales to the shore. Marine biologists say the rescue mission will likely take days.
Whale beachings are common in the region, but one of this size has not been seen in over a decade.
Tasmania last recorded a mass stranding in 2009 involving around 200 whales.
Rescuers from the Tasmanian Marine Conservation Program arrived late on Monday and found three groups of whales across Macquarie Heads – a remote tip of the island with a limited vessel and road access.
About 200 of the mammals had washed up on a sandbar near a boat ramp, while 30 others were found several hundred metres away. Another 30 were found further inland along Ocean Beach.
Many of the whales are in “relatively inaccessible” locations, posing a challenge for rescuers.
However, some of the whales closer to deeper waters have been successfully guided out.
A team of about 40 trained rescuers began to “re-float” a small number of whales on Tuesday morning – using equipment to push the animals off a sandbar into deeper waters.
“Normally we’re dealing with animals high and dry on the beach. This is different. We’ve got animals semi-buoyant so it probably won’t take too much to re-float them – just involves a bit of grunt,” said wildlife biologist Dr Kris Carlyon.
Once the whales are doing well in the water, the next step is to get them further out.
Dr Carlyon told reporters this could be a challenge against the strong tide. Boats might be used to help the manoeuvre.
He added many of the animals may simply be too big or in an unsuitable location. Pilot whales can grow up to seven metres long and weigh up to three tonnes.