Thorong La Pass at 5,416 metres is the geographic and emotional centrepiece of the Annapurna Circuit. It's the highest single pass in the entire Himalayan trekking network commonly crossed by non-mountaineers, and getting across it safely is not a matter of fitness — it's a matter of acclimatisation, timing, and judgement. This guide covers everything we tell our groups in their pre-trek briefing, plus the things you'll only learn on the trail.
What Thorong La actually is
Thorong La is a saddle between two peaks: Thorong Peak (6,144m) to the north and Khatung Kang (6,484m) to the south. The pass sits between them at 5,416m. Crossing it means climbing from High Camp at 4,500m to the pass — a vertical gain of around 900 metres — then descending nearly 1,600 metres to Muktinath at 3,800m on the western side. The total day is 15–18 kilometres of walking with 900m of ascent and 1,600m of descent. Most groups take 8–10 hours.
The pass is not technical. There is no roped climbing, no glacier crossing in normal conditions, no requirement for ice axes or crampons (though in early spring or late autumn, micro-spikes are useful). What it requires is the ability to maintain a slow, steady walking pace at thin air for several hours, sometimes in cold and wind that is significantly worse than anything you'll experience lower on the trek.
The acclimatisation that makes it safe
The single largest risk factor for Thorong La is not the altitude itself — it's arriving at the pass without having spent enough time at intermediate altitudes for your body to adapt. The cardinal rule of high altitude is that above 3,000 metres you should not gain more than 500 metres of sleeping altitude per day, and you should take a rest day every 1,000 metres of cumulative gain.
Our standard itinerary builds in rest days at Manang (3,500m) and a slow climb from there to High Camp (4,500m) over three days. We monitor pulse oximetry every morning and evening from Manang onward. Oxygen saturation should remain above 80% at 3,500m and above 75% at 4,500m. If yours drops below those thresholds, we descend and re-attempt — we do not push on.
Acclimatisation is not just about the pass-day itself. It's about everything that comes before. A trekker who has properly acclimatised will find the pass crossing genuinely difficult but manageable. A trekker who has rushed the lower sections will find it impossible.
The day itself: hour by hour
The crossing typically starts between 4am and 5am from High Camp. The reason is weather: the pass tends to close in by mid-morning as winds pick up and afternoon storms develop. Crossing in clear, cold, still conditions is far more comfortable than crossing in 60kph winds with horizontal snow.
4am: Breakfast at High Camp. Most trekkers struggle to eat at this altitude — appetite suppression is normal — but you must force down at least 500 calories. Porridge, eggs, toast, tea.
5am: Headtorches on. Leave High Camp. The trail climbs steeply for the first 30 minutes through scree and rocky steps. Stars overhead. Bitter cold.
6:30am: Sunrise. The eastern peaks light up. You're at around 4,800 metres. Take it slowly. Breathe deeply.
8:30am: You reach the false summit. The pass is still 30 minutes further on. Many trekkers get demoralised here. Keep walking.
9:30am – 10:30am: The actual pass. Prayer flags, a small tea house, the sign reading 5,416m. The view to the west opens: Dhaulagiri, Tilicho Peak, the Kali Gandaki gorge dropping 4,000 metres below. Take photographs. Drink hot tea. Rest for 20–30 minutes — but no more, because the cold will set into your hands and feet.
10:30am – 2:30pm: The descent. The first hour is steep loose scree — this is where most trekking poles get broken. After dropping to about 4,500m, the trail becomes gentler. You'll pass through alpine meadows and eventually drop into the upper Kali Gandaki valley.
3pm: Muktinath. Hot showers. Real food. Sleep.
What can go wrong, and what to do about it
Altitude sickness (AMS): Headache, nausea, dizziness, loss of appetite, sleep disturbance. Mild symptoms are normal above 4,000m. If you have moderate or severe symptoms, do not attempt the pass. Descend to Manang and re-attempt after 48 hours, or end the trek.
High Altitude Pulmonary Edema (HAPE): Wet cough, shortness of breath at rest, blue-tinged lips. Life-threatening. Immediate descent and helicopter evacuation. Do not attempt the pass.
Weather closure: If wind speeds exceed 50kph or visibility drops below 50 metres, the pass is closed. Wait at High Camp for 24 hours and re-attempt. Tea house owners will have current conditions.
Cold injury: Frostbite of fingers, toes, and ears is the most common injury on Thorong La in winter conditions. Wear two pairs of gloves (liner + insulated outer). Wear merino wool socks under waterproof boots. Cover all exposed skin with a buff.
Knee injury: The descent from the pass is harder on knees than the ascent. Use trekking poles. Pack a knee brace if you have a history of knee problems.
Gear specifically for the pass day
You'll be walking from -10°C to +10°C across the same day. You need to be able to add and remove layers quickly without stopping for long.
- Base layer: Merino wool, long sleeve.
- Insulation: Fleece mid-layer + down jacket. The down jacket comes off as you ascend and your body heats up.
- Shell: Wind-resistant outer (waterproof is nice but the priority is wind).
- Bottom layer: Thermal long johns under trekking trousers. A waterproof outer trouser layer for the descent if snow is present.
- Extremities: Warm hat that covers ears, balaclava or buff, glove liners + insulated outer mittens, gaiters.
- Footwear: Broken-in waterproof trekking boots with ankle support. Micro-spikes in your daypack if any snow is expected.
- Daypack contents: 2 litres water, 1 thermos hot tea, snacks (3–4 bars), spare gloves, headtorch, sunglasses (UV is extreme at 5,400m), sunscreen SPF50+ for face, lip balm, camera with spare battery (cold drains them fast).
The mental side
The hardest part of Thorong La is not the physical climb. It's the moment around 7am when you're at 5,000 metres, you've been walking for two hours in the cold, the pass still looks impossibly far above you, and you start to wonder why you signed up for this. Every trekker hits this moment. Most push through. Some don't.
The way through is to stop looking up. Walk one step. Then the next step. Don't think about how far the pass is. Don't think about the descent. Just the next step. The pass will appear when it appears, and the moment you walk through those prayer flags is one of the most emotional experiences in trekking. We have watched grown men cry. We have watched grandmothers high-five. The mountain rewards persistence.
Final thought
Thorong La is not the hardest pass in the Himalayas. There are technical climbs, longer crossings, more dangerous terrain in plenty of other places. What makes Thorong La special is that it is reachable by an ordinary person who is willing to walk slowly for two weeks and respect the rules of altitude. Almost anyone reading this can stand at 5,416 metres if they prepare properly. That accessibility — combined with the genuine drama of the crossing — is what makes the Annapurna Circuit one of the great walks of the world.
