The whales were located by conservation department staff flying over Golden Bay at the top of the South Island.

About 20 of the 124 whales which first beached at Puponga Beach on Tuesday, have died.

The whales were first refloated on the Wednesday afternoon high tide with tired rescuers recalled several hours later when some of the pod began returning to shallow water.

Conservation department spokeswoman Trish Grant said staff were again being assembled Thursday in case they were needed to herd the whales back out to sea.

"But they're still in Golden Bay southeast of where they were yesterday, so there's a concern they will restrand.

"The crucial time will come this afternoon when the tide is coming in."