A kayaker owes his life to a determined friend and the kindness of a stranger with a Spa pool after spending 40 minutes in Auckland's chilly waters.

The man, aged in his thirties, capsized his kayak while trying to anchor off Achilles Point, East of Ladies Bay, about 7am.

Police Maritime Unit sent a search team out after receiving a call from a witness on the shore.

Constable Alison Campkin said when they found the kayak empty, they expected the worse.

"We automatically thought this is a missing person search."

The cold and windy conditions did not bode well for the man's survival chances, especially as he was not wearing a wetsuit, she said.

Fortunately, unbeknownst to police, the man was with a fellow kayaker when he tipped into the water.

Clinging to the friend's kayak, the man spent 40 minutes in the water being dragged to shore.

Campkin said he told police afterwards he was suffering hypothermia by the time he reached land.

"He was turning blue in the water."

The pair knocked on a stranger's door who took the man to their Spa pool to warm up.

After recovering in the hot tub, Campkin said the man dropped in on Maritime's office to thank the team.

He told them he felt very lucky to be alive and grateful to the people who helped him.

- © Fairfax NZ News