There has been some good news for hundreds of volunteers working to save whales stranded off New Zealand's South Island.

Just over 400 pilot whales beached themselves off New Zealand's South Island on Friday local time, followed by a second pod of 240 at the same spot the following day.

But when exhausted volunteers returned to the remote coastline on Sunday morning to resume their rescue efforts, they saw that all of the second pod had refloated and made their way back into the water.

Image: It is not known why the hundreds of whales stranded themselves

They were milling around in the shallow water so experts will be watching closely to check that they don't strand themselves again.

Department of Conservation spokesman Herb Christophers said: "We had 240 whales strand yesterday in the afternoon and we were fearful we were going to end up with 240 dead whales this morning.


"But they self-rescued, in other words the tide came in and they were able to float off and swim out to sea."

Image: Volunteers formed a human chain in an attempt to stop the whales returning to shore

In total, more than 650 of the animals have stranded themselves along a three-mile stretch of coastline at Farewell Spit in the past two days.

Hundreds of volunteers had flocked to the remote spot after the first group of whales were discovered, but about three-quarters of that pod were already dead when they were found.

Image: More than 400 whales have been found stranded on a New Zealand beach Image: Most of the pilot whales were dead by the time they were spotted on Friday morning Image: The whales were discovered in Golden Bay, the northern tip of New Zealand's South Island Image: But volunteers are hoping about 100 of the pilot whales can be saved Image: On Saturday, however, another pod of about 240 whales stranded itself in the same spot Image: Volunteers continue to try to save the stranded animals and hope to refloat them on the next high tide Image: An urgent plea has gone out for more volunteers to join the hundreds already at the scene Image: It is one of the country's largest recorded mass whale strandings Image: The precise cause of the stranding is not known /

Nevertheless, rescuers spent the daylight hours on Friday trying to keep the whales cool and calm as they waited for the high tides.

Some of the whales were refloated but many beached again that night.

On Saturday, the people braved the threat of sharks and stingrays to form a human chain in an attempt to encourage the whales to swim into deeper water and not to return to the bay.

Image: The scene at Farewell Spit, where hundreds of volunteers have come from around New Zealand to try to save stranded whales

About 80 of that first group survived.

Farewell Spit, on the northern tip of the South Island, has been described as a whale trap, as its long coastline can be difficult for whales to navigate away from.

It is believed whales end up stranded as they try to escape predators, chase prey too far inland, or try to protect a sick member of their pod.

Image: Farewell Spit, where hundreds of whales have stranded in the past few days

The number of calves and mothers in the pods suggested that the stranding could also be linked to the seasonal migration and the area is also known to be difficult for whales to find their way around.

Mr Christophers told Sky News that Farewell Spit is "very shallow and the sand keeps building up in that area and has done for thousands and thousands of years".

Friday's stranding was the third-biggest in the country's history. The largest one on record was in 1918, when about 1,000 pilot whales came ashore on the Chatham Islands.