The flight from Nepalgunj at about 150 m to Simikot at about 2,910 m takes under an hour, and the passes north sit at 4,580 m and about 4,990 m. Take at least two rest days in Simikot, sleep low at Kermi, and never ride Simikot to a pass inside 24 hours.
The profile in numbers
This is the specific shape of the problem in this district. General acclimatisation physiology, the rules of thumb and what the symptoms of altitude sickness actually are belong on the altitude sickness and acclimatisation guide, which is the page to read first if any of this is new.
| Point | Approximate elevation | The gain, and what it means |
|---|---|---|
| Nepalgunj | about 150 m | The Tarai. Hot, flat, sea-level physiology |
| Simikot, by air | about 2,910 m | Roughly 2,760 m in under an hour |
| Kermi | about 2,700 m | Lower than Simikot. The sleeping stop that works |
| Nara La (Nara Lagna) | 4,580 m | About 1,880 m above Kermi |
| Hilsa | 3,720 m | The descent from Nara La is the recovery |
| Selma Lake | about 4,570 m | About 1,870 m above Kermi |
| Nyalu La (Nyalu Lagna) | about 4,990 m | More than 2,000 m above Simikot |
Why the flight is the problem
Almost everyone arrives in Humla by air, because flights into Simikot remain the dependable way in. That flight is short, comfortable and does something to a body that no walking approach would do: it takes you from Tarai heat to nearly 3,000 m in less time than a bus takes to cross a city.
There is no acclimatisation on the way. On a trekking approach anywhere else in Nepal, the days spent getting to 2,900 m do the adaptation work invisibly. Here, none of that happens, and you step off the aircraft at an altitude where a meaningful proportion of people will feel it within a few hours.
The consequence is that the first two days in Simikot are not spare time to be optimised away. They are the acclimatisation, and they are the only acclimatisation the profile offers before the passes.
Two rest days in Simikot
Take at least two full days in Simikot before going anywhere higher. That is the working rule from this district and it is not conservative.
Spend them usefully rather than lying down. The pattern that actually helps is walking high and sleeping low, and Simikot has an obvious way to do it: the trail north of the runway to the Lagnapau viewpoint at roughly 3,200 m, about an hour and a half up and the same back. It gains a few hundred metres and returns you to sleep at 2,910 m, which is exactly what the body wants. The Humla skyline post covers what you see from up there.
Drink more than feels necessary, eat properly, and skip alcohol. And treat a headache that is not improving as information rather than an inconvenience.
Sleep at Kermi
The northern route out of Simikot goes down before it goes up, which is a gift the profile does not otherwise offer. Kermi sits at about 2,700 m, lower than Simikot, and it is the standard first sleeping stop for a reason: it lets a body consolidate at moderate altitude before the big gain, without wasting a day.
From Kermi, the next real altitude is a long way up. Selma Lake at about 4,570 m and Nara La at 4,580 m are both close to 1,900 m above it, and those gains have to be broken into stages with a night in between wherever the route allows. Phendol exists as a camp for exactly this reason.
Anyone doing the northern route as a trek gets this pacing automatically, because walking is slow. Anyone on wheels does not.
Why wheels make it worse
This is the part of the Humla profile that is specific to how people now travel here, and it is the reason this post exists.
A vehicle can take you from Simikot at about 2,910 m to a pass at nearly 5,000 m inside a day. Gaining 2,000 m on wheels in 24 hours is dangerous, and the danger is disguised by how easy it feels: you have not exerted yourself, you are not tired in the way a walker would be, and the symptoms arrive at the top of a climb rather than partway up it.
The rule is straightforward. Never go from Simikot to Nyalu La in a single day. Sleep at Kermi, and use Phendol or an equivalent camp to break the rest of the climb. Riding to Selma Lake and back from a low sleeping altitude is a different and better proposition than sleeping high after a fast gain.
Arriving in Humla overland has one genuine advantage here, and it is this. The road from Surkhet climbs over days, and a body that has come up the corridor arrives at Simikot already partly adapted. That does not make the road the sensible way in for most people, but it is worth knowing that the slow arrival is the physiologically kind one.
Descending is the treatment
There is no hospital in Humla, no hyperbaric facility, and no reliable helicopter evacuation, because evacuation depends on weather that a bad day at altitude usually does not have. What there is instead is height that can be given back.
The response to worsening symptoms is to go down, immediately, and to keep going down until they improve. On the northern route that means back toward Kermi. Nothing else on the list of interventions matters as much, and no schedule, permit or booking is worth arguing about against it.
This is also why the group structure imposed by the restricted-area rules is not purely bureaucratic. Two people minimum and a registered guide means somebody else is watching, and somebody who has seen this before is making the call. The permit guide covers how that system works.
Building an itinerary that respects the profile
The rules turn into a shape, and the shape is not complicated. Two full days at Simikot doing short walks that gain height and give it back. Then down and north to sleep at Kermi. Then the climb staged as above, using Phendol or an equivalent camp rather than pushing through to the high ground in a day.
What that costs is time, and time is the thing every itinerary is trying to save. The trade is worth making because the alternative is not a slower trip, it is an abandoned one. Somebody who goes high too fast comes down, and coming down consumes far more of the schedule than the rest days would have.
Build slack in for weather as well. Flights into Simikot are cancelled routinely and a delayed arrival should push the rest of the plan back rather than compress the acclimatisation. Anyone whose schedule cannot absorb two lost days should not be planning a pass at the end of it.
What Simikot has if something goes wrong
Less than people assume, which is the reason the rules above are not conservative. Simikot has a district-level health facility and pharmacies of the kind found in a small hill bazaar. It does not have a hospital in the sense that a serious altitude case would need, and there is no hyperbaric chamber in the district.
Evacuation is by air and by air only, which means it depends on flyable weather. The circumstances that produce a bad day at altitude are frequently the circumstances that ground aircraft, and a plan built on the assumption of a helicopter is a plan with a hole in it.
Insurance that explicitly covers high-altitude evacuation is worth having and is not a substitute for any of the above. The intervention that always works here is descent, and it is available for free at any hour.
The flight out, and why it is not the end of it
The return to Nepalgunj is the reverse of the arrival and it is physiologically easy: losing 2,700 m in under an hour is what the body wants rather than what it fights. Nobody gets altitude sickness going down.
What does catch people is the schedule around it. Flights out of Simikot are weather-dependent and delays of days are ordinary rather than exceptional, which means the last stage of any Humla trip needs its own margin. Anyone with an international connection booked tight behind a Simikot departure is planning to be disappointed.
The other thing worth knowing is that a few days at altitude does not make the next trip free. Acclimatisation fades within weeks, so a second visit is planned from the same starting point as the first. The honest account of first days at altitude covers what that adjustment actually feels like.
Who finds this profile hardest
Susceptibility to altitude is individual and does not track fitness, and the best predictor anybody has is how they responded to it on a previous occasion. The altitude sickness guide covers that general ground. What follows is only what it means against this particular profile.
What does make the Humla profile harder than most is the speed of the arrival. On a trekking approach elsewhere in Nepal, a body that adapts slowly has days to do it before anything demanding happens. Here the ascent is a flight, so somebody who adapts slowly discovers it at nearly 3,000 m on the first afternoon rather than on day four.
Anyone with a heart or lung condition, anyone pregnant, and anyone on medication that affects breathing or fluid balance should discuss this specific profile with a doctor before committing, and should do it early enough that the answer can change the plan. The same applies to travelling with young children, where symptoms are harder to read.
None of that is a reason not to go. It is a reason to build the itinerary around the possibility that one person in the group will need to descend, and to agree before departure that if that happens, it happens without a discussion.
Before you travel. Humla is a restricted border district and conditions change without notice. Roads close, flights are cancelled, permit rules and fees are revised, and the Hilsa crossing opens and shuts to different categories of traveller. Confirm the current position with the District Administration Office in Simikot, the Department of Immigration, or a registered local operator before you commit to a route.
Frequently Asked Questions
How high is Simikot?
About 2,910 m. The flight from Nepalgunj at roughly 150 m takes under an hour, which is a gain of around 2,760 m with no acclimatisation on the way.
How many rest days do you need in Simikot?
At least two full days before going anywhere higher. Spend them walking high and sleeping low rather than resting completely, for instance the trail to the Lagnapau viewpoint at about 3,200 m and back down to sleep in town.
Where should you sleep on the way north?
Kermi, at about 2,700 m, which is lower than Simikot. The route descends before it climbs, and that stop lets a body consolidate before the long gain toward the passes. Break the rest of the climb with a camp such as Phendol.
Can you ride from Simikot to Nyalu La in one day?
You physically can and you should not. That is a gain of more than 2,000 m in 24 hours, and doing it on wheels hides the risk because there is no exertion to warn you. Sleep low first and break the climb.
Is arriving by road better for acclimatisation?
Yes, in that one respect. The corridor from Surkhet climbs over several days, so anyone arriving overland reaches Simikot already partly adapted. That is not on its own a reason to choose the road, which is slower and far less reliable than flying.
What do you do if someone gets altitude sickness in Humla?
Descend immediately and keep descending until symptoms improve. There is no hospital in the district, no hyperbaric facility, and helicopter evacuation depends on flyable weather. Losing height is the treatment that is always available.
Are the passes higher than Simikot by much?
Considerably. Nara La is 4,580 m and Nyalu La about 4,990 m, against Simikot at about 2,910 m. Selma Lake, below Nyalu, is about 4,570 m. Every one of them is a large gain from any sleeping altitude on the route.