Petzl 100KM Ultra
Northburn 100km
Cromwell (Northburn Station)
Race guide
Updated 29 June 2026
The Northburn 100km, run under the banner of the Petzl 100KM Ultra, is one of New Zealand's most demanding hundred-kilometre races. Set entirely on Northburn Station above Cromwell in the Central Otago high country, the course covers 103 km with 5034 m of climbing and a high point of 1666 m. The terrain is raw, exposed tussock and schist ridge country – there is almost nowhere to hide from the sun, wind or cold. Two distinct loops depart and return to the Start/Finish Marquee at 233 m, meaning your crew can see you at the halfway mark and again at the finish, but in between you are deep in the hills on your own. The combination of relentless vertical, technical underfoot conditions and Central Otago's extreme temperature swings makes this race genuinely hard to the final kilometre.
Course & Terrain
The race is structured as two loops from the Start/Finish Marquee at Cromwell (233 m). Loop 1 climbs immediately and aggressively, passing the Water Container Point at 15 km (930 m) before cresting the Alpine Aid Station at 25 km near the 1662 m high point of the course. From there the route descends steeply to the Mirror Corner marathon turnaround at 37 km (495 m), then climbs and runs back to the marquee to complete Loop 1 at 50 km (237 m). Loop 2 is longer and, for most runners, tougher on fatigued legs: the course climbs again to the Leaning Rock Aid Station at 64 km (1472 m), a sustained ascent of roughly 1235 m from the start of that loop. It then descends to the TW Aid Station at Tokarahi Woolshed (90 km, 504 m) before a final push back to the Finish Marquee at 102.6 km (174 m). Underfoot the course is tussock grassland, loose schist scree, rocky ridgelines and station 4WD tracks – reliable footwork and ankle stability are essential throughout.
Decisive Climbs & Where the Race Is Won or Lost
There are two pivotal ascents that define this race. The first is the opening climb from the start to the Alpine Aid Station at 25 km: covering roughly 1429 m of gain in 25 km, it sets the physiological tone for the entire day. Going out too hard here, chasing the ridge in the morning cool, is the most common way runners blow up well before halfway. The second and more decisive climb is the ascent to Leaning Rock at 64 km (1472 m), tackled after 50 km of already hard racing. By this point accumulated fatigue, any nutrition deficit and the thermal stress of a Central Otago afternoon all compound. Runners who have not adequately refuelled and rehydrated at the Loop 1 crew point will feel the Leaning Rock climb far more than those who have been disciplined. The long descent from Leaning Rock down to the Tokarahi Woolshed at 90 km is where positions shift – it is runnable but still demands respect on tired legs, and poor foot placement on loose schist can end a race in seconds.
Pacing & Fuelling Strategy
With 5034 m of climbing over 103 km, the effective grade-adjusted distance is considerably longer than the raw number suggests. Plan your time budget around the two major ascents and do not let the relatively low starting altitude (233 m) fool you into early pace. Leave the marquee conservatively, hike the steep pitches on Loop 1 and arrive at the Alpine Aid Station (25 km) still feeling controlled. The Loop 1 finish at 50 km is your critical crew point: use it fully. Change socks, address any hot spots, eat a real meal if your stomach allows, and refill all fluid and calorie reserves. The cut-off is midday on Day 1 at the finish (102.6 km), so calculate your required average pace backward from that hard deadline when building your race plan. Fuelling-wise, the exposed nature of the course means sweat rates are high in warm conditions; begin hydrating before you feel thirsty and target consistent calorie intake from the start rather than playing catch-up on Loop 2. The TW Aid Station at 90 km is your last resupply before the finish – do not arrive there in a calorie deficit.
Conditions to Expect
Northburn Station sits in Central Otago, New Zealand's most continental climate zone. Race day temperatures can swing from near freezing on the pre-dawn ridgelines above 1600 m to well over 30 °C in the schist bowl country by mid-afternoon. The high point of 1666 m is fully exposed to wind, and conditions can change rapidly; carry mandatory gear (typically including a waterproof shell and insulation layer) and know how to use it. UV radiation at altitude in this part of the South Island is intense – sunscreen, sun-protective clothing and a hat are not optional. Wind on the exposed ridges can sap energy faster than the gradient alone suggests. Early starters on Loop 1 will experience the coldest part of the course during the pre-dawn climb to the Alpine Aid Station, so have accessible layers for that section and be ready to strip them before the descent heats up.
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Checkpoints & cut-offs
⚠ Auto-researched from public sources — aid stations and cut-offs may be incomplete. Confirm against the official roadbook before race day.
0 km · 233 m · Sat 06:00
15 km · 930 m · —
25 km · 1662 m · —
50 km · 237 m · —
64 km · 1472 m · —
70 km · 1382 m · —
82 km · 1001 m · —
102.6 km · 174 m · Sun 12:00
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Course data researched from public sources — verify against the official roadbook.