Not all heroes wear capes and many are four-legged, like Marley the labrador who helped rescue a small dog swept out to sea at Petone on Sunday.

"We'd been on a nice walk along the beach and we were walking back from the lagoon area," Marley's best friend and owner Steve Sheppard told Checkpoint's Lisa Owen.

"I saw a lot of people walking along, staring out to sea and I thought … this is probably just dogs having fun.

"Then I realised there was a couple of people looking quite concerned and an older lady crying and looking incredibly distressed."

He said he saw what looked like a foxy, highland terrier dog out in the water, looking distressed and agitated.

"Its little paws were splashing up and down and it was yelping and everything.

"It was swimming in a line but it was like it was getting pushed out to sea.

Along the walkway there is a two-metre drop down to the water, he said.

"So there was no way for it to come up to the beach, and the dog was really distressed.

"There was an amazing lady… she'd sort of stripped down and was wading in after the dog, trying to catch it, but she said as soon as she got near, the dog got scared and sort of moved away.

"I'm looking around going, 'hmm, might be time for me to jump in and help out here'.

"And next thing I know my dog's jumped off the walkway into the sea and started swimming towards the distressed dog."

Photo: Supplied

Mr Sheppard said he was totally surprised.

"He's never had any training like that, he's a wonderful dog, awesome soul, a really positive boy.

"He just jumped in and swam towards the dog, and the dog just looked a bit shocked.

"He swam towards the dog, went up to him and sort of nuzzled him, and did what I'd describe as like a tugboat - went around the sea side of the dog and sort of nudged him, and that encouraged the dog to turn around towards shore."

Marley stuck with him as much as he could on the swim back, Mr Sheppard said.

"Then there was another gentleman… stripped down to his underwear and jumped straight into the sea, to go and grab the dog and then pass him up to the very grateful owner.

"Marley our dog likes swimming but I've never seen him do that before - jump off and just sort of go out to the dog and steer him in to shore.

"But then when the other guy jumped out Marley swam back to me, so I had to jump down and lift Marley back up, all 35kg of him.

"Then some lovely person went and got towels and things for people to dry off."

He says the worst thing is not knowing who the other people were that helped in the rescue.

"The adrenaline kicked in, when we realised that everyone was okay, we just went our own ways. It's just classic low-key New Zealand behaviour I think.

"The thing that was so amazing for me in this world of social media we live in, not one of us had stopped to take photos or videos or anything like that because I think we were all just thinking gosh we might jump in and help the dog."

Mr Sheppard said he has huge respect for the two people who jumped in the water to help.

"The sea wasn't exactly tropical, so for that lady to be paddling along behind [the small dog] and the guy to dive in… it was a really selfless act by them, and our dog Marley.

"So it was just really nice, it shows you the sense of community we have and that there are real-life heroes out there."

Photo: Supplied

He said Marley was quite spoiled afterward.

"He came home and was really tired after his big swim. So he sat curled up on his blanket, but he had some steak for dinner, and had a few treats during the day.

"Once I lifted him out of the water, a couple of people looking had some treats for their dogs that they were walking, and they gave him some treats. So he really enjoyed that I think.

"He didn't really know what all the fuss was about."