Pussy cat, pussy cat, where have you been?

If only animals could talk.

Perhaps Sweetie the domestic cat could then explain how she ended up stranded on a centre pontoon under the Tauranga Harbour Bridge three days after going missing.

The tabby family cat was found by kayakers at the base of a central pillar of the bridge, in the deepest part of the channel and more than 150 metres from shore.

How she got there remains a mystery.

Mavis Rimaha has owned Sweetie for seven years and said the moggie always greeted her when she returned to her Papamoa home from work.

"She normally comes out for a meal because she normally knows what time I come home. But this time she didn't," Ms Rimaha said.

After a few hours on New Year's Eve, Ms Rimaha and her daughters became worried and began searching their neighbourhood.

"We were terrified," Ms Rimaha said. "We couldn't find her ... so we went out looking for her."

When the Tauranga SPCA rang three days later to say Sweetie had been found underneath the harbour bridge, Ms Rimaha could not believe it.

But the penny also dropped.

"When she was little she had a great habit of jumping into anyone's car," Ms Rimaha said.

"My daughter was over from Huntly and went for a swim at Whareroa [marae] on New Year's Eve. They didn't realise the cat must have been in her van. She must have got a fright and climbed out and took off.

"But I'd love to know how she got so far out in the water."

SPCA inspector Jason Blair said he initially struggled to believe a report of a cat stranded on a pontoon.

Kayakers who found Sweetie waved down a passing jetskier, who then notified the Tauranga Harbourmaster and the SPCA was called.

As Mr Blair was being ferried out by the harbourmaster, he thought he was probably responding to a hoax, he said.

"I've been out with the harbourmaster before, for other matters, but we were sort of wondering if this was truthful or not."

However, as they approached they could see a "very calm" Sweetie in the hands of the kayakers who discovered her,"right in the middle channel of the harbour".

Mr Blair said Sweetie was friendly and purring as they took hold of her and it was obvious she was someone's pet.

When Sweetie was taken back to the SPCA, she was scanned for a microchip and Ms Rimaha's details showed up. The Rimaha family and Sweetie were soon reunited.

"It just goes to show the benefits of microchipping your animals," Mr Blair said.

Anyone interested in microchipping their pets should contact their veterinarian or the Tauranga SPCA.