Within Blenheim railway station, I can see a business called The Wine Station, whose signage offers wine tasting, food, and an ''artisan market''. Blenheim is the hub of New Zealand's Marlborough wine region, so there must be sauvignon blanc tastings galore here.

I'll never find out, however, as I'm just passing through aboard the Coastal Pacific. This train is one of New Zealand's great rail journeys, passing down the east coast of the South Island. This railway took decades to build. From the ferry port at Picton in the 1870s, it inched south until it finally reached Christchurch in 1945. The pay-off for 21st century travellers is a marvellous tourist route that takes in everything the South Island has to offer: ocean, mountains, vineyards and wildlife.

However, nature in this country gives and takes away. The 2016 Kaikoura earthquake shattered the rails along the east coast, and it wasn't until late 2018 that passenger services resumed.

So I'm feeling privileged to be aboard one of the first runs of the 2019-2020 season (the train doesn't operate over winter), with the extra good fortune of sunny weather for our six-hour journey south.

The day starts with the Interislander ferry from Wellington on the North Island across the Cook Strait through the beautiful Marlborough Sounds to Picton. There's about a 90-minute gap between the first ferry arrival of the day and the 2.15pm southbound train, so we have coffee in the nearby township, a pretty locale surrounded by steep green hills. Picton is behind us as we passed the vineyards of Blenheim, heading south towards an emptier and more spectacular landscape.

The carriages of the Coastal Pacific have been designed specifically to cater to tourists, with forward-facing seats set up in a 2+2 configuration, and some sets of four facing each other across tables. In one carriage is a cafe, and there's an open-sided observation car from which to take photos unimpeded by window reflections.

Seats are fairly comfortable, with plenty of leg room, and viewing is enhanced by large windows supplemented by smaller angled panes above. This is fortunate, because I've ended up on the non-ocean side of this particular train. Unfortunately it's impossible to reserve a specific seat, as KiwiRail's computer system magically decides the night before where to best place each passenger.

No matter, the views are good, as is the recorded commentary provided at regular intervals via a headphone jack.

As we pass above broad Cloudy Bay, the commentary mentions it was the site of one of the earliest Maori settlements. This leads to a retelling of the legend of Maui, the demigod who fished up the North Island with a hook while standing on a canoe which became the South Island.

Past Seddon (named for a significant 19th century prime minister, says the commentary), we sight Cape Campbell with its distinctive lighthouse, and a strange landscape dominated by Lake Grassmere. This large body of water is walled off artificially into rectangular ponds, from which a vast amount of salt is gathered after evaporation.

Beyond the small town of Ward (another PM), the railway starts to hug the Pacific coast and does so until we're well past Kaikoura. About 4pm we suddenly have an expansive view of the Pacific Ocean on our left, with nothing but blue as far as the eye can see. As the commentary points out, the next major land mass in that direction is South America.

Yellow grass on low dunes undulates between the train and the shore, and the sight of all that cool water is welcome on this warm, sunny day. Suddenly, a small field with sheep appears between us and the ocean then we're back to the dunes and the ocean beyond.

I'm struck by how under-populated it seems along this coast, with its long stretches of empty black sand. The endless rolling waves breaking towards us are mesmerising as we track alongside them.

The commentary likes to throw in the occasional historic drama to spice up the journey. As we near the mouth of the Clarence River, it recounts the 1886 wrecking of the steamship SS Taiaroa near here. On that terrible evening, the vessel was grounded offshore in bad conditions, and 36 people lost their lives when its lifeboats capsized.

Farther on, we reach a zone of offshore black and white rocks, home to a fur seal colony. Once endangered by hunters and having dwindled from an estimated two million down to 50,000, the seals' numbers are now increasing under protection. The rocks become bigger and craggier as we progress and take on interesting shapes - I spot one which vaguely resembles the Sphinx.

Just before Kaikoura we get our first proper view of the Kaikoura Range, the set of mighty snow-capped mountains which will form a dramatic backdrop to our ride. After we pass the town, we enjoy the most impressive scenery of the journey, with simultaneous mountains to our right and waves breaking on the coast to our left.

We take a late lunch in the cafe car and although the hot dishes are reheated, rather than prepared from scratch, it's good quality cuisine sourced from Wellington-based caterer Wishbone. The vegetable lasagne has an excellent cheesy filling including pumpkin, spinach, broccoli and capsicum. It goes well with a bottle of Monteith's Golden Lager from the popular South Island brewer. Other choices include Thai chicken curry, roast chicken and lamb shanks, as well as sandwiches and soups.

Eventually, we leave the coast and head inland past rugged hills. Soon we're back in farming country, though there are still scenic highlights such as the Hurunui River, which winds alongside the rails for a while. We're never short of views of natural beauty on the Coastal Pacific, and they take us all the way south to Christchurch.