More than 130 melon-headed whales, a member of the dolphin family usually found in the deep ocean, beached in Japan this morning.
There have been frantic efforts by locals and coastguards to save them.
Rescuers were battling to stop the creatures' skin from drying out as they lay on a beach about 100km northeast of Tokyo.
Other melon-headed whales were being carried in slings back towards the ocean.
Several animals from the large pod had been badly cut, with many having deep gashes on their skin.
A journalist at the scene said that despite efforts to get the dolphins into the water, some were being pushed back onto the beach by the tide soon after they had been released.
A number of the creatures had died, he said, and were being buried.
"We see one or two whales washing ashore a year, but this may be the first time to find over 100 of them on a beach," a coastguard official said.
The pod was stretched out along a roughly 10km-long stretch of beach in Hokota, Ibaraki, where they had been found by locals early this morning.
Melon-headed whales, also known as electra dolphins, are relatively common in Japanese waters and can grow to be two- to three-metres long.
Despite international criticism, Japan hunts minke and pilot whales off its own coast, and has for many years also pursued the mammals in the Antarctic Ocean using a scientific exemption to the international moratorium on whaling.
It has never made any secret of the fact that meat from the animals is also consumed.
However, a UN court ruled last year that its hunt was a commercial activity masquerading as research, and ordered it be halted.
Tokyo, which insists whaling is a tradition and labels environmental campaigners as "cultural imperialists", has vowed to restart a redesigned southern ocean whaling programme, possibly later this year.
