123 pilot whales have stranded themselves on New Zealand's South Island beach.

Over 100 volunteers and conservation workers are trying to save as many as they can, in what is being called one of the "biggest mass strandings in a decade."

According to the BBC, the whales have beached in two groups, one near the top of Puponga Beach at Farewell Spit and the second further out.

Another pod of 40 whales has been seen offshore near the stranded groups but has not yet come aground, officials say.