Express yourself: The splendours of New Zealand are best seen by rail

Grand Central, St Pancras, Milano Centrale – and, er, Britomart? The main station in New Zealand's largest city sounds as though it is named after a discount car-parts retailer. In fact, Auckland's Britomart Transport Centre occupies a handsome Victorian building on Queen Elizabeth II Square, and is apparently named after a character from The Faerie Queene.

It is also the northern terminus of New Zealand's longest train ride – the 12-hour haul south to the capital, Wellington – known as the Overlander. And as if to hint at the views that lie ahead, it is run by Tranz Scenic.

Standing on the platform, I noticed that my luggage was being loaded on board by staff who wouldn't stop smiling. If I was to come across railway employees this friendly in England, I'd be suspicious. Are they going to try to sell me something? Are they drunk? Am I?

Perhaps the early start had made me paranoid; I'm not normally ready to make the journey from my bed to the bathroom at 7.25am, let alone a trip almost the length of the North Island. Once on the train, I still couldn't get over the affable staff: I watched as an elderly passenger discussed the contents of her sandwiches with an avid audience of two grinning, female employees. Perhaps Tranz Scenic staff get an extra chapter on customer relations in their training handbooks.

I wrestled my brain back to contemplation of the onward journey. The track that the Overlander would take us along that chilly Sunday was originally planned towards the end of the 19th century, a main trunk line deemed necessary to lend full steam to New Zealand's industrial progress. The service got going in 1909 and has continued ever since, even surviving a threatened closure in 2006 that was called off due to public outcry and a subsequent increase in passenger numbers.

It is one of three train services that Tranz Scenic operate; the other two are on the South Island. The train from Picton to Christchurch is known as the TranzCoastal, while the line across the mountains from Christchurch to Greymouth is the TranzAlpine. Both of these services run daily, as does the Overlander during the summer; in winter it runs from Friday to Sunday.

The first two-and-a-half hours, covering the 85 miles from Auckland to the sprawling city of Hamilton, revealed little of what lies in store. As we passed through the misty Whangamarino Wetlands and across the monstrous Waikato River, I listened to the train manager who – in between serving me an all-day breakfast roll in the buffet car and chatting to yet more garrulous elderly women – provided commentary as we approached station stops or passed through areas of interest.

One such area is a piece of track known as the Raurimu Spiral, boasting more curves and elevation than a Miss World contestant. It was constructed in 1898 by engineer RW Holmes to combat a particularly steep gradient; seven miles of twisting track cover a straight-line distance of three-and-a-half miles. We were told the (possibly apocryphal) story of the driver of a long goods train who, navigating the spiral one night, brought proceedings to a sudden halt. He was concerned by the appearance of red tail-lights up ahead; getting out to investigate what they belonged to, he found himself confronted by his own guard's van.

Some of the stations have more appealing names than "Britomart": one, just before the halfway point, is called simply "National Park". Here, passengers on the southbound service are given a half-hour break to get some fresh air; northbound travellers get only five minutes. The park in question is Tongariro, which was established in 1887 – the first national park in New Zealand and the fourth in the world. On a clear day it is possible to spot the three volcanoes at its heart: Tongariro, Ngauruhoe and Ruapehu. In winter, it is a popular spot for skiing.

The Tranz Scenic's services offer a number of such stops: you can either get off to stretch your legs or disembark for good. (One other option at National Park is to hop on board the service travelling north, which calls at the station about 20 minutes after the other one heads south, allowing a full-day there-and-back trip from Auckland.)

I was back on board the moment the whistle sounded (warnings that the train will leave without late passengers are repeated throughout the journey). I took the opportunity to sit in the observation carriage, located at the rear of the train, with a huge panoramic window and a semi-circle of lounge seating. It's an excellent spot to relax and take in the scenery. We passed through rolling farmland and caught glimpses of small, wooden churches and sprawling hardware stores in towns such as Palmerston North, Levin and Paraparaumu.

Another, albeit windier, option for seeing the sights is the Overlander's open-viewing platform; the TranzCoastal and TranzAlpine services offer whole carriages exposed to the elements. Here you feel even closer to the landscape as it rattles past; you can also take photos without the reflections cast in the windowed carriages. You might want to grip the handrail a little more tightly as you pass over one of the many viaducts en route; the highest on the Overlander line – Makatote Viaduct – is 79m (260ft) tall.

On arrival at the nation's capital my luggage proved easy to find on the platform by dint of a colour-coded tag. (This ease of baggage conveyance remained intact when I made my way from Wellington and onwards from Picton to Christchurch on the TranzCoastal service the following day. Despite the fact that a ferry journey is thrown into the mix, my case was there to greet me at the end of the day.)

The Interislander voyage through the Cook Strait takes about three hours from Wellington. The views through the Queen Charlotte Sound are beautiful: deep blue water and lush, green vegetation. At one point, we were treated to the spectacle of a school of common dolphins leaping gracefully alongside the prow.

Once on dry land, passengers have to make their own way from the ferry to the train station. This is a simple transition, and even if you do somehow manage to get lost en route – as I did – picturesque Picton is a compact enough place: you'll make it to the station in time.

The TranzCoastal – as you might imagine – passes right along the Pacific coast, providing ample opportunity for penguin and seal spotting. You can also get off the service at Kaikoura station to do some whale watching: the station sits on the appropriately named Whaleway Station Road.

The initial stage of the TranzCoastal journey takes you through Blenheim, a pretty town that is the gateway to Marlborough, the largest grape-growing region in New Zealand. If you stay on board all the way to Christchurch you'll pass through 22 tunnels along this route, as the train navigates the imposing Kaikoura mountain range. A spell in the outside viewing carriage while going through one of these is an impressive acoustic experience.

Travelling on the TranzCoastal is the only way to get this close to the Eastern coastline, as no roads pass nearby. That's not the only benefit of choosing train over a car: this way all members of your party get to admire the views – and the desire to follow a map is one of curiosity rather than necessity.

The final element in the New Zealand railway trilogy is the TranzAlpine between Christchurch and Greymouth. This four-and-a-half hour journey traverses the sweeping Canterbury Plains, a patchwork of multi-coloured fields that is the largest area of flat land in the country. Then it climbs through the gorges and valleys of the Waimakariri River to Arthur's Pass, named after Arthur Dobson, in recognition of his inaugural survey of the area in 1864. It wends its way down through the Southern Alps and beech rain forest to the west coast.

The beauty of these train journeys is that you can appreciate the dominance of New Zealand's landscape over its inhabitants. Over half of the population of four million people live in four of the towns and cities I'd passed through: Auckland, Hamilton, Wellington and Christchurch. This majestic country is forthright in its unwillingness to be tamed. As the train rumbled along tracks that bend to the landscape's every whim, it was hard to resist the temptation to break out in quiet applause.

Travel essentials: New Zealand

Getting there

* The only direct flights from the UK to Auckland are on Air New Zealand (08000 284 149; airnewzealand.co. uk), from Heathrow via Los Angeles or Hong Kong. Airlines offering connections include Qantas (0845 7 747 767; qantas.co.uk) from Heathrow via Melbourne or Sydney, Emirates (0870 243 2222; emirates.com) from Heathrow, Gatwick, Birmingham, Manchester, Newcastle and Glasgow via Dubai, and Singapore Airlines (08448 002 380; singaporeair.com) from Heathrow and Manchester.

Getting around

* The best way to sample New Zealand's three long-distance railways is with a Scenic Rail Pass (00 64 4 495 0775; tranzscenic.co.nz), operating in the same way as a hop-on/hop-off bus service, but over the course of a week or two.

More information

* Tourism NZ: newzealand.com