The Ball Pass trek is a test of stamina and skill rewarded by unmitigated thrills, writes Paul Rush.
The Caroline Face of Aoraki/Mt Cook is a monumental slab of rock and ice that keeps me engrossed for hours.
Periodically it bursts into life like an angry giant shedding his white cloak while roaring in ill-tempered rage.
I never tire of studying its endless expanse of suspended ice sheets, defying gravity as they cling to the near-vertical face.
I try to capture on film the changing light effects under the setting sun.
It is hauntingly beautiful and serene between the massive ice falls.
The sheer-sided 2000m face has a high level of danger for intrepid mountaineers.
The jagged south ridge leading to the low peak of Aoraki, was first climbed by Sir Edmund Hillary and his mentor Harry Ayres prior to the ascent of Everest in 1953.
I'm just content to admire its whipped cream slopes and precipitous rock walls from a safe distance.
These are moments to savour and remember always.
When the first flush of dawn floods the towering ice cliffs, I see the telltale puff of powder snow that heralds an avalanche.
Instantly, a thunderous roar shatters the still air.
Countless tonnes of ice tumble down the tortured rock face, leaving a curtain of pulverised ice particles suspended in space as a white mist.
Our group lingers awhile to marvel at the sight and then pushes on through the rock-hard ice field. Suddenly we are standing atop Ball Pass, with breathtaking views of snow-capped peaks in every direction.
It's a grand spectacle of soaring mountains, eternal ice sheets and great buttresses of fragmented rock and glistening ice.
For me the alpine world has an undefined mystique, exciting and threatening at the same time.
To stand on a 2120m-high mountain pass and allow your eyes to follow the jagged ridges up to the triple summit of Aoraki/Mount Cook is the ultimate exhilarating experience.
The Ball Pass trek is a three-day guided traverse from the Tasman Valley over the flank of Mount Cook into the Hooker Valley.
It's both a physical crossover and an emotional transition from tramping to alpine climbing.
The climb involves a technical change from the use of trusty Leki poles on forest tracks to the alpinist's ice axe and crampons on the slippery mountain slopes. Mastering the technical skills and standing atop the pass is the climax of my trip.
Our enthusiastic group of amateur climbers first assembled at The Hermitage in Mount Cook Village.
A Land Rover soon whisks us up the stony margins of the Tasman River, braided into channels of pale glacial blue water, coloured by rock flour sediments scoured out by the glacier.
In the Ball Shelter area the rock-studded Tasman Glacier has sunk 130m below the old moraine walls.
This is a glacier in serious decline, although still the southern hemisphere's longest at 27km.
When George Mannering and Arthur Harper made the first Ball Pass crossing in 1890, the glacier was 100m higher than it is today.
The jumble of shattered greywacke rock that is called Ball Spur has little semblance of a track.
I climb the precipitous slope cautiously, staring at the heels of the five climbers ahead who are as lithe as leprechauns.
After a five-hour slog nothing can restrain my involuntary "Yee haa!'' as Caroline Hut comes into view.
On day two, our skills training begins with snow and ice-travel techniques. With crampons strapped on securely, we sidle across steep slopes, slowly gaining confidence and adjusting to the deep bite of the crampon points into the ice.
We learn the critical skill of self-arresting on snow surfaces.
Initially by turning to face the slope and digging in the toes in a spider-like manner, and then moving on to a bottom-slide using trekking poles as outriggers.
The next day begins with an early wake-up call, a substantial breakfast and an 8am departure.
As we assemble our gear, a young chamois steps up on a prominent rock 100m away, in full silhouette against the sun-washed Caroline Face.
We call her Sally and shout a greeting, but her curiosity at seeing strange bipedal mammals is overcome by her innate caution and she quickly disappears from view.
The view from the pass is inspiring but also daunting.
Deep in the valley we can see the Hooker Glacier terminal moraine lake and above that, Mt Sefton and the Sealy Range.
We are buffeted by sudden wind gusts and I recoil at the steepness of the descent before us, which starts with an ice slope of 40deg.
Our guides explain that a slip during this part of the descent will mean sliding into a rock pile 300m below.
The morning sun has not reached the western slopes of the pass, so the ice is as hard as concrete, leaving us no chance of self-arresting.
This graphic description of "clear and present danger'' provides a sharp focus to my mind.
One acquires skills quickly when life depends on it, so progress on the initial descent is quite good, as we follow a seemingly endless traverse along the rock-faces below Mt Rosa.
The scale of the mountains are staggering.
Even after an hour of tortuous descent from the pass, the Hooker Glacier floor is still a steel-grey jumble of moraine debris far below us.
Finally a flat alpine tussock plateau is sighted and identified as the lunch stop.
It's known locally as the "Playing Fields''.
I think the end is in sight, until our guide casually mentions that there are still three and a-half hours to go.
This illustrates the deceptiveness of scale in the Southern Alps.
The altitude and grandeur of the surrounding mountains shrinks the valley floor in my mind's eye.
Pressing on along the high Hooker terraces through a profusion of alpine plants - Mt Cook lilies, buttercups, mountain daisies, cushion plants and snow grass - we reach the camp at White House Hill.
The Ball Pass crossing is an unforgettable experience.
Under the guide's direction one learns how to master the alpinist's game, training in the snow and ice under the tall white ramparts of our beloved Aoraki.
It is a game with a serious input of energy and concentration, but how satisfying it is when you win and conquer the terrain.
Check list
Getting to Aoraki/Mt Cook
• Mount Cook Airlines flies from Christchurch and Queenstown. Intercity buses connect with Christchurch and Queenstown.
• Road access is on SH8 from Timaru and SH80 from Lake Pukaki to Mount Cook.
• Ball Pass Crossing times are; day 1, six hours. day 2, training, four hours. day 3 over the pass, 10 hours.
Activity planning
• Day outings at Mount Cook can be planned in consultation with hotel and visitor centre staff in a way that reflects family interests, physical fitness and changing weather patterns. Don't miss the guided boat cruise to the terminal face of the Tasman Glacier.
• The most settled weather conditions are from January to April, when maximum daytime temperatures range from 15-23degC. The Doc Visitor Centre displays daily weather forecasts.
Where to stay
• Caravan parks are in the White Horse Campground, 2.5km from Mt Cook Village, and Glentanner Park Centre, 18km before Mt Cook.
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