Six lifeguards piloting two inflatable rescue boats around New Zealand were welcomed by friends and family at the end of their 5200km journey at the Viaduct Harbour yesterday.

The trip began in Auckland on January 5 and was the first circumnavigation of New Zealand in an inflatable boat less than 4m long.

"Thirty-four days ago we set off, and we took a pounding on our first day. And we were kind of going, 'What have we got ourselves into'," said lifeguard and accountant Ash Matuschka.

"But I guess the body started getting used to it, and we just pushed on and on. And now here we are, and it feels damn good to be back."

Mr Matuschka - who was joined by Andrew Lancaster, Jason Harvey, Blake Ingram, Matt Buswell and Anthony Morgan - said he organised the trip after reading a book by British adventurer Bear Grylls, who crossed Canada's Arctic Northwest Passage in a rigid inflatable boat.

It occurred to him that a trip around the country in rescue boats would be a fitting way to celebrate 100 years of surf lifesaving in NZ.

The group began each day at 4.30am and had a reserve driver, Jason Glew, and land crew supporting them.

Four lifeguards took to two boats while two took a rest and planning day. Everyone stayed on land overnight.

The trip took the group past "stunning" remote coastline, and gave them a new appreciation of New Zealand, Mr Matuschka said.

"We spent one lunchtime around the bottom of Stewart Island in a bay where who knows the last time somebody was there. Had lunch with a big sea lion sitting down there, and the water was crystal blue. I could have sworn we were at a Pacific island."

Equally impressive was the hospitality shown to the crew when they came in to land at the end of a hard day on the water, he said.

"It makes you really proud to be a Kiwi. The surf clubs welcomed us ... as you can imagine, but also in all these places that were in-between where there were no surf clubs - Haast, Timaru - they were just great."

Near St Clair Beach in Dunedin the group bumped into Tim Taylor, a 24-year-old Tauranga man trying to set the record for the first continuous solo loop of New Zealand by a kayak.

More of a surprise was when the support crew was called on to rescue a drowning woman while waiting for the boats to come ashore at the remote Oruaiti Beach on the East Cape.

"A guy came running up to us and his girlfriend had got into trouble ... I can't imagine what the guy was thinking. He comes out of the water and he looks up and there's a lifeguard truck," Mr Matuschka said.

The lifeguards were kept company by dolphins, albatrosses, yellow-eyed penguins, seals - and the odd shark.

"One of them nudged the boat," said Mr Lancaster. "That gave us a big fright. It was eight to 10 foot and it was sunbathing ... We went straight into it."

Not that it was always so exciting, especially because the noise of the 30-horsepower outboard motors made conversation impossible. "There's a lot of thinking done," Mr Matuschka said.