Revellers were seen partying in hot pools on the shores of Lake Taupō 12 hours before two bodies were discovered in the water today.

A local man who was at the lake last night said around 7.30pm he walked passed two women and a man at the popular Hot Water Beach spot who appeared intoxicated.

Police are today trying to work out how two people died after their bodies were discovered by a walker submerged in the water around 7am.

The man, who did not want to be named, said one of the women in the group was sitting in a car that remained parked up at the same lakeside spot this morning close to the crime scene.

He saw one of the women emerge from a pool wrapped in a towel while the man was dangling his legs in the hot water.

"I think at that stage they were intoxicated," he said, describing their behaviour as loud and drunken.

He did not recognise any of the group.

The man, who was taking his family to a nearby hotel for swim, returned to the same spot an hour later when a blood-curling wail pierced the air.

"We'd finished our swim. We heard the noise and we jumped in the car and headed to where it was coming from. It was a horrible whiny noise," he said. "By the time we got there the cops were leaving."

He watched the group continue to party loudly, after the police left.

"You could still hear them in the water. They were yelling because they were drunk.

"We saw them sculling a bottle as we drove in a second time."

When he learned of the double deaths this morning he was left feeling numb.

"I was very sad, very bummed out actually.

"My wife was saying we should have done more but what could we do?"

Police remain at the lake as investigations continue into the deaths.

A tent had been erected over a thermally-heated rock pool where the bodies were discovered.

Police said they were working to establish the identity of the mystery pair.

A spokesperson said a scene guard would remain in place on the edge of the lake while detectives worked out how the pair met such a tragic end.

Earlier today, Taupō Mayor David Trewavas said to know two people had lost their lives was a tragedy.

"To wake up on a beautiful crystal-clear day, the lake is so pristine, and for someone to come across two people dead is very, very unfortunate.

"This is a very, very sad day."