Thorong La Pass (5,416 m): Altitude, Difficulty & Crossing Guide

Updated on: 6 Jul, 2026

Reading time: 8 min

Quick answer: Thorong La (5,416 m) is the high point of the Annapurna Circuit and one of the highest trekking passes in the world. You cross it on a long, pre-dawn day from High Camp. Altitude is the main risk, so slow acclimatization and an early start matter most.

Thorong La Pass sits at 5,416 m (17,769 ft). It is the high point and the crux of the Annapurna Circuit. It links the Manang valley in the east with Muktinath and Mustang in the west (Wikipedia, retrieved 2026-06-18). The crossing is not technical. However, it is a long, hard day. Up there, the air holds only about half the oxygen of sea level. So success comes down to acclimatization, an early start, and good weather.

Key Takeaways

• Thorong La is 5,416 m, one of the highest passes crossed on any popular trek.
• The crossing day is long. It means a pre-dawn start, a climb of about 1,000 m, then a big drop to Muktinath.
• It needs no climbing skills. But it does need acclimatization and fitness.
• Altitude sickness is the main risk. The Manang rest day and a slow pace keep you safe.

This guide covers the altitude, the difficulty, the crossing day, and how to prepare. The pass is the heart of both the 12-day Annapurna Circuit Trek and the longer 15-day version via Muktinath and Mustang.

Quick facts

How high is Thorong La, and why does that matter?

At 5,416 m, your body works at roughly half its sea-level oxygen all day. That is the most important fact about the pass. It is not the steepness that makes it hard. Instead, it is the thin air. At this height, even fit trekkers move slowly, breathe hard, and tire fast.

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This is why the Annapurna Circuit builds in a rest day at Manang (3,540 m) before the pass. It also climbs gently through Yak Kharka and Thorong Phedi. Your body needs days, not hours, to adjust. So rushing the approach is the most common reason trekkers fail to cross.

What is the crossing day like?

You start very early, around 3 to 4 AM, to reach the pass before the wind builds. Then you descend a long way to Muktinath. A typical crossing looks like this:

• Pre-dawn start from Thorong Phedi (4,540 m) or High Camp.
• A steady climb of about 900 to 1,000 m to the top, slow and breathless in the cold and dark.
• The summit at 5,416 m, marked by prayer flags, with a wide view over the Annapurna and Mustang ranges. It is an emotional, hard-earned moment.
• A long descent of more than 1,500 m down to Muktinath (3,800 m). It is tough on the knees, but it brings you fast into richer air.

The whole day usually takes 7 to 9 hours. Your guide checks conditions first. So if snow or a storm moves in, the guide will turn back, which is the right call.

How difficult is Thorong La Pass?

Thorong La is strenuous, but a fit, well-prepared trekker can cross it with no climbing experience. There is no technical ground. You need only good boots and warm layers, plus micro spikes if there is snow. What makes it hard is the mix of altitude, an early start, the cold, and the long day.

In our experience, the trekkers who cross easily do three things. First, they train beforehand. Second, they take the Manang rest day seriously. Third, they walk the approach slowly. Fitness helps, but acclimatization matters more. So this is not a pass to attempt without those gradual days behind you.

How serious is altitude sickness on Thorong La?

Acute mountain sickness (AMS) is the real danger on the pass, and it rises sharply with height. In one study of Nepali Himalaya trekkers, AMS affected about 15% at 4,000 to 4,500 m and 51% at 4,500 to 5,000 m (PubMed, retrieved 2026-06-18). Crossing at 5,416 m puts you above that range. So prevention is everything.

Here is how to stay safe:

• Acclimatize. Do not skip the Manang rest day or rush the climb.
• Walk slowly and drink plenty of water. Symptoms often start around Manang (3,500 m): headache, nausea, dizziness, and poor sleep.
• Tell your guide early. Our guides carry a pulse oximeter and check you daily.
• Descend if it gets worse. Going down is the best treatment, and Muktinath is a fast descent.

Carry any altitude medication your doctor advises. And never push over the pass with worsening symptoms.

What are HACE and HAPE?

Two rare but life-threatening conditions can develop at this height, and both need an immediate descent. The US Centers for Disease Control splits altitude illness into three types: AMS, high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE) (CDC Yellow Book, retrieved 2026-06-18).

• HACE is the dangerous next stage of AMS. It shows as confusion, drowsiness, and loss of coordination. It can turn life-threatening within 24 hours if ignored.
• HAPE is fluid in the lungs. The signs are breathlessness at rest, a constant cough, and extreme tiredness.

For both, the CDC is clear: descent and oxygen work far better than any medicine. This is exactly why we never push trekkers with worsening symptoms over the pass. It is also why a guide who spots these signs early matters so much. Both are uncommon with good acclimatization. Still, everyone crossing Thorong La should know the warning signs.

What if you cannot cross the pass?

Turning back is a normal, safe choice, not a failure. A good guide plans for it. Weather can close Thorong La with snow or high wind. Or your body may simply not adjust in time.

So what are your options? If the pass is unsafe or you feel unwell, you can rest a day at Manang or Yak Kharka and try again, if your schedule allows. Or you can descend the way you came, down the Marsyangdi valley. Travel insurance with helicopter cover handles the worst case. The mountain will always be there. Pushing on into bad weather or worsening symptoms is the one mistake that turns a hard day into a dangerous one.

What gear do you need for the Thorong La crossing?

The summit morning is bitterly cold and dark, so the right gear keeps you safe. Carry these in your daypack on crossing day. Your duffel goes ahead with the porter.

• Warm layers: thermal base layers, a fleece or down mid-layer, and a windproof, waterproof shell.
• Down jacket for the pre-dawn start and the windy summit.
• Insulated and liner gloves, a warm hat, and a buff for your face.
• Headlamp with fresh batteries for the early start.
• Micro spikes or crampons if there is snow or ice, which is common outside peak season.
• Sunglasses and high-SPF sunscreen for the bright glare once the sun is up.
• Insulated water bottle so it does not freeze, plus high-energy snacks.
• Trekking poles for the long, steep descent to Muktinath.

When is the best time to cross Thorong La?

Spring (March to May) and autumn (late September to November) are the best windows. In both, the pass is most reliably open and clear. In winter (December to February), heavy snow can block Thorong La or make it dangerous. In the monsoon (June to August), cloud and rain cut visibility on the approach.

Even in the good seasons, the pass needs a clear-weather window. So a flexible day or two helps. Your guide tracks the forecast and times the crossing for the safest day.

How do you prepare for Thorong La?

Good preparation is what gets you across. Here is what to do.

• Train for 8 to 12 weeks: cardio plus long hills with a daypack, on back-to-back days.
• Break in your boots, and pack proper warm layers, because the summit morning is freezing.
• Respect the acclimatization plan. The Manang rest day is not optional.
• Carry micro spikes in the shoulder seasons, in case of snow.
• Go guided. A licensed guide is required in the Annapurna region anyway, in force since 2023 and still mandatory in 2026 (Kathmandu Post, 2023; Nepal Tourism Board, 2026). On top of that, a guide reading the weather and your health is your best safeguard.

For the full route and budget, see our Annapurna Circuit cost guide and the wider Annapurna region trekking guide.

Accuracy note: official fees, rules, and hard facts in this guide are cited inline from their sources; trail and price details are Spade Himalaya field research; route details reviewed by Yubaraj Katel, government-licensed trekking guide (Licence No. 19827) with 10 years of experience across the Everest, Annapurna, Langtang, and Manaslu regions.

Author

Pawan Bhattarai

Pawan Bhattarai is a co-founder of Spade Himalaya, a Nepal-based trekking and tour company he started to help share Nepal's mountains with the world. A keen traveller with a background in technology and content, he writes carefully researched guides to help people plan their trip. On the ground, Spade's treks are led by licensed local guides.

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