Efforts to refloat the eight remaining pygmy killer whales on a Northland beach has been somewhat successful.

Twelve of the rare oceanic dolphins stranded on Ninety Mile Beach on Sunday, and four died on the sand.

The remaining eight whales were refloated this afternoon but the decision was made to euthanise two of them after they beached again.

The six surviving whales are now 500m offshore and the Department of Conservation will continue to monitor them over the afternoon.