Arthur's Pass National Park

Listen for a moment. Somewhere above you there may be a sharp, rising cry, half whistle and half shriek, bouncing off the rock. The air here is thin and cool, even in summer, and it smells of wet stone and beech leaves. Underfoot the gravel is grey and loose, washed down from the peaks by countless storms. This is Arthur's Pass National Park, high in the Southern Alps of New Zealand's South Island, where the mountains split the island into two very different worlds.

The park sits right on the Main Divide, the spine of the Southern Alps. Rain that falls on one side runs east toward the Canterbury Plains and the Pacific. Rain that falls on the other runs west to the Tasman Sea. You are standing on a line that decides where water goes. That simple fact shapes almost everything you will see here, from the trees to the rivers to the weather that can change within an hour.

Long before any road or railway, this landscape was known to Māori, the Indigenous people of New Zealand. Ngāi Tahu, the main tribe of the South Island, travelled routes through these mountains. One great reason to make the journey was pounamu, the prized greenstone found on the West Coast. Pounamu was carved into tools, weapons and treasured ornaments, and it was carried across the Alps to communities in the east. The pass you are visiting was part of a much older story of movement and trade.

The name on the map comes from a young surveyor called Arthur Dudley Dobson. In 1864 he explored this route across the Divide, and the crossing became known as Arthur's Pass. Timing mattered. Gold had been found on the West Coast, and thousands of miners were rushing there. Canterbury wanted a direct link to the goldfields, and quickly. Within a couple of years a coach road was pushed through the mountains, and horse-drawn coaches began rattling over the pass.

That road was hard and dangerous. Coaches climbed steep grades, crossed flooded rivers and faced slips of rock and snow. Later came the railway, and with it one of the great engineering efforts in the country's history. The Otira Tunnel, bored straight through the mountains, opened in 1923. It runs for more than eight kilometres beneath the Divide. When it opened, it was among the longest railway tunnels in the world. Trains still pass through it today.

Here is a detail many visitors miss. Arthur's Pass was the first national park in the South Island, created in 1929. Only Tongariro and Egmont, both in the North Island, were older. Part of the reason was the railway itself. The new line brought visitors from Christchurch into the mountains with ease, and people began to see this place as something worth protecting, not only something to cross on the way west.

Now look around at the forest, if you are on the eastern side near the village. Much of it is mountain beech. The trunks are slim and dark, the leaves are small and tough, and the forest floor is often open and mossy. Beech can survive the drier, colder conditions that the mountains create on this side. In early summer, look closely at the branches. You may see red and cream flowers on plants that hang from the beech, small mistletoes that add colour to the green.

Cross over the Divide to the west, and the world changes. The rainfall there is far heavier, because moist winds from the Tasman Sea hit the mountains and drop their water. The forest becomes thick and tangled, with tree ferns, mosses and climbing plants. Travellers often notice the difference within a few kilometres. It feels a little like driving from one country into another, without ever leaving the same range of hills.

That cry you may have heard belongs to the kea. The kea is a large parrot, olive green, with a bright orange flash under its wings when it flies. It is the world's only alpine parrot. Kea are clever, curious and famously bold. They will study a car, pull at rubber seals and investigate bags left on the ground. Locals tell many stories of missing sandwiches and damaged windscreen wipers. But kea are threatened, and human food harms them, so please never feed them.

The small settlement of Arthur's Pass village grew up around the road and the railway. It is a quiet place, with a handful of buildings, a railway station and the park's visitor centre. Many walks start close by. One of the best known leads to the Devil's Punchbowl Falls, where a tall ribbon of water drops down a dark rock face into a cool, misty basin. On a still day you can hear the falls well before you see them.

For stronger walkers, routes climb above the bushline onto open tussock and bare rock. Avalanche Peak is one of the most popular climbs, with wide views of ridges, glaciers and river valleys. But this is real alpine country. Snow can fall in any month, cloud can close in fast, and rivers can rise after rain. The visitor centre gives current advice on weather and track conditions, and it is wise to check before you set out.

In the valley below the pass, look at the Waimakariri River and its tributaries. These are braided rivers, wide beds of grey shingle with many shallow channels weaving across them. The channels shift after every flood. Braided rivers like these are rare around the world, but in Canterbury they are a familiar sight. They carry the mountains, piece by piece, down toward the sea, and they give the valleys their wide, open look.

Before you move on, take one more look at the line of peaks above you. Notice how the cloud often clings to the western side while the eastern sky stays clearer. Listen again for water, for wind in the beech leaves, perhaps for the call of a kea. People have crossed these mountains for centuries, on foot, by coach and by train. Today, for a few moments, you are part of that long line of travellers... standing on the divide between two seas.