Not so long ago, motorists who headed out from Auckland on Route 27 across the Hauraki Plains were generally city families going to their “bach” (holiday shack) on the Coromandel Peninsula or farmers hurrying back to the barn after a visit to the Big Smoke. But, these days, a thickening stream of traffic continues over the Kaimai Ranges and drops down into Tauranga, on the western edge of the aptly named Bay of Plenty.

Even for New Zealanders who have not visited Tauranga for some time, its extreme makeover from sleepy hollow to next big thing comes as something of a shock: people debating an ambitious museum proposal, swirling around the lobby of the city’s first luxury waterfront hotel, navigating traffic snarls caused by the €395m of roadworks, being carried out in anticipation of urban growth 50 years from now.

Business is on the move, too. The Port of Tauranga, now New Zealand’s largest and the most efficient in Australasia, is winning valuable container business from Auckland’s choked facilities and has increased profits by almost 30 per cent in 2007. Developers are circling, from Irishman Aidan Harrison (who developed Dublin’s Blanchardstown) to local Maori landowners. Nearly 7 sq km of land have been earmarked in and around the city for industrial and commercial uses, including a major technology hub, food manufacturing park and marine refit and boatbuilding precinct.

Gutsy export businesses thrive in Tauranga, developing and marketing the new: from international sport blokarting, to avocado oil. Though the city’s downtown heartbeat falters after sunset, and its creative pulse is hard to find (“trying to get developers to support the arts sector – now that would definitely be development for us,” quips Te Rahui August, 26, a Maori radio and television producer recently recruited by the city’s arts honchos to bridge the culture gap), Tauranga faces the world like an expectant adolescent, all optimism and eagerness.

“You could say we’re all dressed up and ready for the party,” says the port’s chief executive Mark Cairns.

For decades, Tauranga and its twin settlement on the ocean side, Mt Maunganui [the Mount], were synonymous with lazy summer holidays and the quiet life. Land used to be cheap – the city has eight golf courses, for goodness sake. The average Kiwi family could build or park a caravan along the white surf beaches that stretch eastwards around the Bay of Plenty, and for older people Tauranga was a favoured retirement spot.

But in the past decade Tauranga has morphed from Pleasantville into a city on the make. By 2050 its population is expected to double to 220,000 – still not much larger than some European villages. Many of those pouring in – at a rate of 100 a week – are professionals and tradespeople aged 30 to 50. They come from both within and outside New Zealand, lured by jobs and the good life. “The new influx has brought new values,” says mayor Stuart Crosby, who leads a city council with the rather predicatable slogan “live, work, play”.

Graphic designer Reuben Woods, 30, and his wife Melissa, 28, set up a brand-development business in the rapidly growing beachside suburb of Papamoa three years ago. Neither grew up in the Bay of Plenty, but “we looked for a place with surf and a growing economy,” says Melissa. Business has prospered – Woods Creative’s clients include broking house ABN AMRO Craigs and bedding manufacturer Design Mobel, both headquartered in Tauranga, and the couple both get in a surf before work, walking the 100 metres to the beach in their wetsuits.

Silvério Filho, 29, also a surfer, and his girlfriend, Marina Galiotto, 25, are part of Tauranga’s lively Brazilian crowd. Some come with jobs (local IT employers go to Brazil to recruit) while others are travellers who find reasons not to leave. There’s seasonal work (the Bay of Plenty grows the vast bulk of New Zealand’s kiwi fruit and avocado crops), but Filho is hoping that 4iCoNZ, the sporting adventure business he set up a year ago, will work well enough to allow them to stay. Galiotto says: “It’s quiet and safe and we have everything we need.”

Brett Hewlett, 45, couldn’t agree more. “It’s a playground here,” he says. But it’s also becoming a place from which it’s possible to build a multinational business. In 2005, Hewlett took the helm of Comvita, a natural health company aiming to go global with its honey-based products. Half its €41m turnover now comes from high-strength manuka honey (sold as a digestive aid in Asia), but its new focus is honey-based wound dressings. In August it gained FDA approval to sell into the multi-billion-dollar US market. Comvita has been on an overseas buying spree and only 100 of its employees are now New Zealand-based.

Hewlett says: “It’s an easy place to do business from. You can rock up to the airport 30 minutes before take off for an international check-in.” Tauranga’s discovery by high-fliers isn’t entirely accidental. The region has been actively promoted by Priority One, a partnership between the business community and local authorities that was founded in 2001 to develop an economy to support the city’s growth.

Projects administrator Annie Hill says: “It’s a very connected community… and everyone is singing from the same songsheet.” Priority One reports strong international interest in the planned technology park, with its proposed link into the 10-gb-per-second Karen (Kiwi Advanced Research and Education Network). There are no rates holidays or sweetners, as such, she says, only the ones that come with the territory.

Tauranga’s natural assets are a given. The city, embedded in a stunning coastline, is a fishing paradise and backs on to the fertile hinterland. But although its population has grown by 30 per cent in a decade, it has lacked the economic depth to attract young, skilled migrants. Priority One has been “spruiking” Tauranga’s charms in the UK, and this year expects up to 1,000 skilled migrant approvals, up on 600 in 2006.

Over at the Mount, corporate lawyer Murray Denyer, 37, is at his office at Zespri, the kiwi fruit marketing body that relocated from Auckland in 2002. He lives 10 minutes’ walk from work and a minute’s walk from the beach. “Some people are still hesitant to live here,” he says with amazement. Like New Zealand’s €500m kiwi fruit industry, he’s prospering in Tauranga, and he doesn’t look back in angst at the bright lights.

Prices for houses and apartments in prized coastal Mt Maunganui, Papamoa and in the city have rocketed since 2003, fuelled by demand and a strong economy. Buyers can pay upwards of NZ$3m (€1.2m) for premium property (a penthouse with harbour views or beachfront at Mt Maunganui). The average house price in Tauranga is NZ$345,000 (€182,000) for a three-bedroom house on about 800 sq m of land. At the cheaper end, head towards Greerton on Tauranga’s southwestern fringe, where a one-bedroom cottage with garden shed sells for around NZ$230,000 (€121,500).

Weekly rents vary from about NZ$200 (€105) for two bedrooms to an average three-bedroom house at NZ$350 (€185) and NZ$800 (€423) for a five-bed in the city with harbour views. Recommended local property agents are Bayleys, Eves or Frank Vosper. The Bay of Plenty is well serviced by legal firms to help with conveyancing.

Tauranga is the only city in New Zealand with an airport located in its heart, linking to all the key cities including Auckland, Wellington and Christchurch. Tauranga ranks behind those airports as the country’s fourth busiest. The city is connected to Auckland by 246km of rail. In a backward step, passenger services were discontinued in October 2001 but goods are still transported by rail. Auckland is an easy two-and-a-half-hour drive, and Hamilton and Rotorua are an hour away.

Tauranga revolves around the car, though recently the council has opened several cycle tracks and boardwalks, and plans eventually to link coastal, city and rural tracks and walkways. A NZ$750m (€395m) investment in the road network will manage projected population growth. The result will be an expressway taking motorists in and out of the city and facilitating travel around the rest of the region.

Tauranga is divided by a harbour. A bridge joins the CBD and town to the Mt Maunganui beaches. It also links the two sides of the port so is prone to congestion. Nimble tourists tackle the Mount’s summit walk, while the locals like to swim in the Hot Salt Water Pools at the base before retiring to pavement cafés – Slow Fish and Side Track are top choices.

For live music try Wednesday night at the Crème Bar to party or Latitude 37 on a Friday to mellow out. The Fatted Aphid in Piccadilly Arcade is a wireless hotspot with deep armchairs, fine coffee and muffins. The Sebel hotel juts out over Trinity Wharf, and serves New Zealand food.

Tauranga is dominated by its port and the kiwi fruit industry. The port was established in 1873, but business has boomed in the past 15 years and it is now the country’s largest international port.

About 85 per cent of New Zealand’s kiwi fruit crop is grown in the Bay of Plenty in Tauranga’s hinterland. The industry employs 16,000 people. Since 1997 sales have grown from 56 million trays a year to 86 million in 2007 and return to growers per hectare has doubled. Top prize for innovation in the region must go to the father-and-son duo, Paul and Matt Beckett, and their Blokart – a cross between a boat and a go-kart. They have sold 2,000 of them since 2000 and will now manufacture 1,000 a year, having built an international sport on its back. The European Blokart Championships have just been held in Belgium, and the first World Championships are scheduled for 2008 in New Zealand.