Forty-eight pilot whales have restranded at Golden Bay, after spending nearly four hours swimming in deeper water.
Department of Conservation ranger Neil Murray said the whales were refloated this afternoon with the high tide, but had returned to Triangle Flat, near the base of Farewell Split.
A team of DoC staff and volunteers would stay with the whales until dark, keeping them as comfortable as possible.
The whales were expected to refloat in the incoming tide during the night, however it was unclear whether they would move into deeper water, Mr Murray said.
The 48 whales are thought to be from a pod of about 70 which stranded at Farewell Spit yesterday.
Twenty-one of those whales died after becoming stranded, Mr Murray said.
This morning, 63 live whales were found scattered along the beach at Farewell Spit, after refloating and moving through the night.
One of the whales died this morning, however the remaining 62 were refloated this afternoon during the high tide.
While two of the whales died before making it to deeper water, the majority were able to be mobilised.
But despite the efforts of DoC staff and volunteers, 10 whales remained in shallow water and swum further east along the coast of Farewell Spit, eventually stranding about 10km east from Triangle Flat near the base of the spit.
A decision was made to euthanise 8 of the beached whales - after two had died naturally - to give the whales further out to sea a better chance.
However, since then, the 50 whales which had been out at sea had returned and rebeached, with two now dead.
Mr Murray said staff would assess the situation at first light.
"In their current form, we're not confident they'll get themselves off. Last night's whales, they didn't move very far.''
Earlier this week eight whales were euthanised after stranding themselves twice at Farewell Spit. A ninth whale, which had not been seen at the beach, also had to be put down after it became stranded.
Last week 27 pilot whales had to be put down after becoming beached at the spit. A further 12 had already died from natural causes after being stranded.
Mr Murray said the decision to euthanise whales depended on their health and their chances of survival.
It was made by DoC staff, local iwi and volunteers.