08
Aug
Imagine walking on a trail that would normally feel comfortable, but after gaining altitude, every few steps leave you breathing harder. Your heart beats faster, your legs feel heavier, you may develop a headache, and even sleeping can suddenly become difficult. This is what makes high altitude trekking so different from trekking at lower elevations.
So, what happens to your body at high altitude?
The biggest change is the availability of oxygen. As you climb higher, atmospheric pressure decreases. Although the atmosphere still contains approximately 21% oxygen, the lower air pressure means that each breath delivers fewer oxygen molecules to your lungs. Your body must therefore work harder to take in oxygen and transport it to your muscles, brain, heart, and other organs.
These effects of high altitude on the body can begin relatively soon after reaching a higher elevation. You may notice faster breathing, an increased heart rate, unusual fatigue, reduced exercise performance, disturbed sleep, or changes in appetite. At greater elevations, some trekkers may experience headache, nausea, dizziness, or other altitude sickness symptoms.
Altitude is generally considered "high altitude" from approximately 2,500 metres (8,200 feet) upward, although people respond differently and altitude illness can occur at different elevations.
This is where high altitude acclimatization becomes essential. Your body needs time to adapt to the reduced oxygen availability. A gradual ascent allows these physiological changes to happen progressively, while ascending too quickly can increase the risk of acute mountain sickness (AMS) and more serious altitude-related illnesses.
Whether you are planning a Himalayan trek, a high-altitude expedition, or simply travelling to a mountain destination, understanding how altitude affects the body can help you recognize what is normal, identify warning signs, and make safer decisions.
The primary reason high altitude affects your body is the reduction in atmospheric pressure and oxygen availability.
One of the most common misconceptions about altitude is that the percentage of oxygen suddenly decreases as you climb. It doesn't. Oxygen continues to make up approximately 21% of the atmosphere.
What changes is the pressure of the air.
At higher elevations, atmospheric pressure is lower. As a result, there are fewer oxygen molecules in the same volume of air. This means that with every breath, your lungs have access to less oxygen than they would at sea level.
This reduction in available oxygen is called hypoxia, and it is responsible for many of the high altitude effects on the body.
Your body immediately begins responding to this change.
At sea level, your body is accustomed to a relatively high atmospheric pressure and readily available oxygen. As you ascend, the pressure gradually falls.
This is particularly important for trekkers because climbing thousands of metres in a relatively short period exposes the body to an environment it has not yet adapted to.
At altitude, your body attempts to compensate by:
Breathing faster and deeper
Increasing heart rate
Increasing blood flow to important organs
Adjusting how oxygen is transported and used
Making longer-term physiological adaptations during acclimatization
The faster you ascend, the less time your body has to make these adjustments.
This is why how altitude affects the body depends not only on how high you go but also on how quickly you get there and at what altitude you sleep.
When you are trekking, your muscles require significantly more oxygen than when you are resting.
At high altitude, oxygen availability is already reduced. Add several hours of uphill walking, a backpack, cold temperatures, and uneven terrain, and your body has to work considerably harder.
This can result in:
Breathlessness
Increased heart rate
Muscle fatigue
Reduced walking speed
Longer recovery time
Headache or nausea in some people
This is why a trek that feels easy at a lower altitude can suddenly feel much more demanding at 10,000 or 12,000 feet.
The body can adapt, but it cannot adapt instantly.
The first few hours after reaching a higher altitude can feel completely normal for some people. Others may immediately notice changes in their breathing, heart rate, energy levels, appetite, or sleep.
Your response depends on several factors, including the altitude you reach, the speed of ascent, previous exposure to altitude, and individual susceptibility.
Here are some of the most common early effects of high altitude on the body.
One of the earliest responses to the lack of oxygen at high altitude is an increase in breathing.
Your body detects the lower oxygen availability and instructs your respiratory system to breathe faster and deeper. This allows more air to reach the lungs and helps increase oxygen uptake.
You may notice this particularly while walking uphill.
Even a relatively gentle climb can make you feel unexpectedly breathless. You may need to slow down, take more frequent breaks, or use a slower and steadier breathing rhythm.
This is one reason trekkers often ask, "Why do you get breathless at high altitude?"
The answer is that your body is working harder to obtain the oxygen it needs.
Your cardiovascular system also responds rapidly to altitude.
As less oxygen is available, your heart may beat faster to circulate blood and deliver oxygen to your muscles and organs.
Therefore, high altitude and heart rate are closely connected.
A walking pace that feels comfortable at sea level may cause your heart rate to rise much more quickly at altitude.
This does not necessarily mean something is wrong. It can be a normal physiological response during the early stages of high altitude acclimatization.
However, unusual chest symptoms, severe breathlessness, fainting, or other concerning symptoms should never simply be dismissed as "altitude."
Another common experience is high altitude fatigue.
Your muscles have less oxygen available to produce energy efficiently, while your body is simultaneously spending energy adapting to the new environment.
As a result, you may:
Walk more slowly
Need more frequent breaks
Feel that your backpack is heavier
Take longer to recover after a climb
Experience heavy or tired legs
This can happen even to physically fit trekkers.
Fitness helps you manage the physical demands of a trek, but it does not make you immune to altitude-related problems.
Headache is one of the most common altitude sickness symptoms.
A mild headache can occur as the body responds to altitude, but a headache accompanied by nausea, dizziness, unusual fatigue, or loss of appetite can be a sign of acute mountain sickness (AMS).
The important thing is to monitor how the symptoms develop.
A worsening headache should never be ignored simply because you are trekking at altitude.
Altitude can also affect your appetite.
Some trekkers experience:
Reduced hunger
Nausea
Feeling full quickly
Reduced interest in food
Occasionally, vomiting
Loss of appetite and nausea can occur as part of acute mountain sickness.
Even when you don't feel hungry, your body still needs adequate energy to walk and acclimatize. Small, regular meals and easily digestible foods can be useful during high-altitude trekking.
Sleeping at altitude can feel very different from sleeping at home.
You may experience:
Difficulty falling asleep
Frequent waking
Restlessness
Unusual breathing patterns
A feeling that you haven't slept deeply
Sleep disturbance is relatively common during altitude exposure and does not automatically mean you have altitude sickness.
Your body continues adjusting to reduced oxygen availability even while you sleep.
Changes in breathing and fluid balance can result in increased urination during the early stages of acclimatization.
Combined with physical exertion, cold weather, and the dry mountain environment, this can increase your need to pay attention to hydration.
However, drinking excessive amounts of water is not a way to prevent altitude sickness. The aim is adequate hydration, not forced overhydration.
High altitude doesn't affect just one part of the body. Reduced oxygen availability influences the respiratory, cardiovascular, nervous, muscular, digestive, and other systems.
Understanding these changes helps explain why your entire experience of trekking can feel different as you climb higher.
Your lungs are among the first organs to respond to reduced oxygen availability.
As you climb higher, your body increases your breathing rate so that you can bring more air into your lungs.
This is why high altitude breathing often becomes faster and deeper.
During exercise, your muscles require even more oxygen. Therefore, breathlessness becomes particularly noticeable while climbing steep trails.
The question "Why do you get breathless at high altitude?" has a straightforward answer: the lower atmospheric pressure means each breath provides less available oxygen, so your body compensates by increasing ventilation.
As you acclimatize, your body becomes better adapted to the environment.
However, severe breathlessness, especially breathlessness while resting or breathing difficulty that progressively worsens, should not be considered normal.
Your heart has an important role in responding to reduced oxygen availability.
At altitude, your heart may beat faster so that blood can circulate more rapidly and deliver oxygen to your muscles and organs.
This explains the connection between high altitude and heart rate.
You may notice your pulse rising quickly even during relatively slow walking.
Over time, high altitude acclimatization allows your body to become more efficient at coping with the reduced oxygen environment.
However, severe or unusual cardiovascular symptoms should always receive medical attention rather than being automatically blamed on altitude.
Your brain is particularly sensitive to changes in oxygen availability.
One of the most common symptoms associated with altitude exposure is a headache. This is also an important symptom of acute mountain sickness.
So, why does altitude cause headache?
Reduced oxygen availability triggers several physiological changes, including changes in breathing, circulation, and fluid balance. These changes can contribute to headache in susceptible individuals.
A headache after ascending does not automatically mean severe altitude sickness. But a headache accompanied by nausea, dizziness, fatigue, or loss of appetite deserves attention.
More serious neurological symptoms—including confusion, altered mental state, severe loss of coordination, or unusual behaviour—can indicate high-altitude cerebral edema (HACE) and require emergency action.
Your muscles need oxygen to produce energy efficiently.
At high altitude, less oxygen is available, so physical activity can feel significantly harder.
This explains why a person who can easily walk several kilometres at sea level may struggle with a shorter distance at altitude.
High altitude fatigue can make your legs feel heavy and recovery between climbs can take longer.
This is not necessarily a sign that you are physically unprepared. Even trained athletes experience reduced exercise performance when they first reach high altitude.
The best approach is to slow your pace, take appropriate breaks, maintain nutrition and hydration, and allow adequate time for acclimatization at high altitude.
High altitude can affect appetite and digestion.
Some trekkers experience:
Reduced appetite
Nausea
Feeling full quickly
Stomach discomfort
Vomiting in more severe cases
High altitude nausea and loss of appetite can also be symptoms of acute mountain sickness.
Although you may not feel hungry, your body still needs energy during a demanding trek. Small, frequent meals can sometimes be easier to manage than large meals.
Persistent vomiting is particularly concerning because it can cause dehydration and make it harder for the body to cope with altitude.
High altitude sleep can be surprisingly different from sleep at sea level.
Some trekkers find it difficult to fall asleep, while others wake repeatedly throughout the night.
Changes in breathing during sleep can also occur as your body responds to reduced oxygen availability.
This is why a good acclimatization schedule is important. Your body needs time to adjust not only to walking at altitude but also to spending the night there.
Disturbed sleep by itself does not necessarily mean you have altitude sickness. However, if it occurs together with worsening headache, nausea, dizziness, confusion, or other concerning symptoms, it should not be ignored.
High altitude dehydration can become a concern because several factors work together.
Cold and dry mountain air can increase fluid loss through breathing. Physical activity causes sweating, while increased breathing and frequent urination can further influence fluid balance.
Trekkers may therefore feel thirsty, have a dry mouth, or experience fatigue.
Adequate hydration is important during high altitude trekking, but drinking excessive water does not prevent altitude sickness.
The goal is to maintain normal hydration without forcing large amounts of fluid.
High altitude acclimatization is the process by which your body gradually adapts to reduced oxygen availability.
It is one of the most important concepts to understand before undertaking a high-altitude trek.
When you ascend, your body immediately begins responding to the lower oxygen environment. Your breathing becomes faster, your heart works harder, and your body begins making physiological adjustments.
However, these changes take time.
This is why acclimatization at high altitude is not simply about taking a day off from trekking. Even while resting or sleeping, your body is actively adapting to the altitude.
There is no universal number of days that guarantees complete acclimatization.
The time required depends on:
The altitude you are reaching
How quickly you ascend
Your sleeping altitude
Your previous exposure to altitude
Individual susceptibility
Whether your body has had adequate time to adapt
As a general principle, the higher you go, the more gradual your ascent should be.
For example, altitude-travel guidance commonly recommends limiting increases in sleeping elevation to approximately 1,600 feet (500 metres) per day above 9,000 feet, with an additional acclimatization day for every approximately 3,300 feet (1,000 metres) gained.
This is why responsible trekking itineraries do not simply calculate distance. They consider altitude gain, sleeping altitude, ascent rate, and acclimatization days.
There is no guaranteed method to completely prevent altitude sickness, but you can reduce your risk by following sensible altitude practices.
Avoid rapid gains in sleeping altitude whenever possible.
An acclimatization day gives your body time to adjust before you climb higher.
Drink regularly and maintain adequate hydration without forcing excessive amounts of water.
Your body needs sufficient calories and nutrients for both trekking and physiological adaptation.
Alcohol can interfere with sleep and may contribute to dehydration, making the early adjustment period more difficult.
Don't try to maintain your sea-level walking speed. A slow and steady pace is often more sustainable at altitude.
Do not ignore persistent headache, nausea, dizziness, unusual fatigue, or other altitude sickness symptoms.
One of the most important principles of altitude safety is:
If your symptoms are getting worse, do not go higher.
No summit, pass, or campsite is more important than your health.
Acclimatization is not a race. It is your body's gradual process of learning to function in an environment where oxygen availability is lower.
One of the most common questions trekkers have before a Himalayan trek is: what happens to your body at 8,000, 10,000, or 12,000 feet?
There is no single altitude at which everyone suddenly experiences the same symptoms. Individual responses to altitude vary considerably. Your previous exposure to high altitude, speed of ascent, sleeping altitude, physical condition, and individual susceptibility can all influence how your body responds.
However, as you climb higher, the available oxygen decreases because atmospheric pressure continues to fall. This places increasing demands on your respiratory and cardiovascular systems.
Understanding what happens at different elevations can help you prepare for high altitude trekking and recognize why a trail that feels easy at a lower elevation can become much more challenging higher in the mountains.
At approximately 8,000 feet (2,400 metres), many people can still function relatively normally, especially if they have ascended gradually. However, this is around the elevation where altitude-related problems become increasingly relevant.
You may begin noticing:
Faster breathing during physical activity
Increased heart rate
Reduced exercise performance
Mild fatigue
Headache
Disturbed sleep
Slight changes in appetite
Altitude illness is generally considered a concern from around 2,500 metres (8,200 feet) upward, particularly when a person ascends rapidly without adequate acclimatization.
This does not mean that everyone reaching 8,000 feet will experience high altitude sickness. Many people adjust well, particularly when the ascent is gradual.
The important factor is not simply the number on the altimeter. How quickly you reach that altitude matters enormously.
At approximately 10,000 feet (3,050 metres), the effects of altitude can become more noticeable, particularly in people who have not acclimatized.
You may notice that:
Walking uphill requires considerably more effort.
You become breathless more quickly.
Your heart rate rises faster.
Your muscles fatigue sooner.
You need more frequent breaks.
Sleep may become disturbed.
Your appetite may decrease.
Headache or nausea may develop.
This is where high altitude acclimatization becomes particularly important.
A trekker who normally walks quickly at sea level may need to adopt a much slower pace at 10,000 feet. This is not necessarily a reflection of fitness. The body is simply working with less available oxygen.
For this reason, well-planned high altitude trekking itineraries generally avoid unnecessarily rapid increases in sleeping altitude.
At approximately 12,000 feet (3,650 metres), the physiological effects of altitude can become significantly more noticeable.
You may experience:
Greater breathlessness during exertion
Increased fatigue
Reduced physical performance
Headache
Nausea
Reduced appetite
Disturbed sleep
Longer recovery after physical effort
At this elevation, the difference between trekking at sea level and trekking in the mountains can feel dramatic.
A moderate climb can leave you breathing heavily, and even routine activities such as packing your backpack or walking around camp may require more effort.
This is why trekkers heading towards high Himalayan passes and camps need adequate acclimatization at high altitude.
The key principle is simple:
The higher you climb, the more important gradual ascent becomes.
Above approximately 15,000 feet (4,500 metres), you are entering extreme altitude, where the physiological stress of reduced oxygen availability becomes much greater.
Exercise performance can decline substantially, and the body has less capacity to compensate for the reduced oxygen environment.
At these elevations, careful acclimatization, conservative ascent schedules, experienced leadership, weather awareness, and emergency planning become particularly important.
Trekkers should never assume that being physically fit makes them immune to altitude illness.
One of the most important things to understand before high altitude trekking is the difference between normal physiological adjustment and altitude sickness.
When you first reach altitude, your body naturally responds to reduced oxygen availability. Faster breathing, increased heart rate, reduced exercise performance, and some sleep disturbance can occur as part of this adjustment.
However, certain symptoms indicate that your body may not be coping well with the ascent.
During the early stages of acclimatization, you may experience:
Faster breathing during exercise
Increased heart rate
Mild fatigue
Reduced exercise capacity
Temporary sleep disturbance
These responses occur because your body is attempting to adapt to the lower oxygen environment.
With adequate high altitude acclimatization, many of these effects become more manageable.
However, symptoms should not progressively worsen.
Acute Mountain Sickness (AMS) is the most common form of altitude illness.
It typically develops after ascending to a higher elevation, particularly when the ascent is too rapid for the body to acclimatize.
Common altitude sickness symptoms include:
Headache
Fatigue
Dizziness
Nausea
Loss of appetite
Difficulty sleeping
Headache is particularly important when assessing AMS.
The symptoms often appear within several hours to a few days after ascent.
Importantly, altitude sickness is not a sign of poor fitness. A highly trained athlete can develop AMS, while a person with average physical fitness may acclimatize without significant problems.
Previous successful high-altitude trips also do not guarantee that you will not develop altitude sickness on another trek.
The progression of symptoms matters.
If you develop mild symptoms after ascending, the safest approach is generally to stop gaining altitude and allow your body time to adjust, while monitoring your condition and following professional medical or trek-leader guidance.
However, if symptoms become worse despite resting at the same altitude, continuing higher can be dangerous.
Watch particularly for:
Severe or worsening headache
Repeated vomiting
Increasing weakness
Difficulty walking normally
Confusion
Changes in mental alertness
Breathlessness while resting
These can indicate a more serious altitude-related problem.
Never try to "push through" worsening altitude symptoms simply to reach the next campsite, pass, or summit.
Most people who experience altitude-related symptoms do not develop severe complications. However, anyone travelling to high altitude should know about two potentially life-threatening conditions:
High-Altitude Cerebral Edema (HACE)
High-Altitude Pulmonary Edema (HAPE)
These are medical emergencies.
High-Altitude Cerebral Edema, or HACE, is a severe form of altitude illness involving swelling of the brain.
It can develop as a progression of severe acute mountain sickness and requires immediate action.
Important symptoms include:
Severe or worsening headache
Confusion
Altered mental state
Unusual behaviour
Difficulty walking
Loss of coordination
Extreme drowsiness
Reduced consciousness
One of the most important warning signs is loss of coordination.
For example, if a trekker who was previously walking normally suddenly struggles to maintain balance or walk in a straight line, this should be treated as a serious emergency.
A person with suspected HACE needs immediate descent and urgent medical care.
Do not allow the person to continue climbing.
Do not simply assume they need to sleep and will feel better the next morning.
At altitude, deterioration can occur rapidly.
High-Altitude Pulmonary Edema, or HAPE, is another potentially life-threatening altitude illness.
HAPE occurs when fluid accumulates in the lungs, making it increasingly difficult for the person to breathe.
Symptoms can include:
Increasing breathlessness
Difficulty breathing while resting
Persistent cough
Weakness
Reduced ability to exercise
Chest tightness or discomfort
In severe cases, frothy or blood-tinged sputum
One important distinction is between normal exertional breathlessness and breathlessness at rest.
It is normal to breathe harder while climbing steep terrain at altitude. It is not normal for a person to become progressively breathless while sitting or lying down.
HAPE is a medical emergency.
Immediate descent to a lower altitude is essential, together with urgent medical evaluation and appropriate emergency treatment.
A trekker showing signs of HAPE or HACE should not continue ascending.
This is why responsible trekking operators should have emergency communication, evacuation procedures, trained staff, and a clear plan for dealing with altitude-related emergencies.
There is no guaranteed method to completely prevent altitude sickness, but trekkers can significantly improve their chances of adapting safely by following sensible altitude practices.
The most important principle is:
Give your body time to adapt.
Here are practical high altitude trekking tips to support acclimatization.
Rapid ascent is one of the major risk factors for altitude illness.
Whenever possible, increase sleeping altitude gradually rather than making large jumps in elevation.
Above approximately 3,000 metres, commonly used altitude-travel guidance recommends limiting increases in sleeping elevation and incorporating additional acclimatization days as altitude increases.
Your trek itinerary should therefore consider sleeping altitude, not just the total height you reach during the day.
An acclimatization day is not a wasted day.
It gives your body additional time to adapt before you climb higher.
Many responsible trekking itineraries include an acclimatization day at an appropriate elevation, sometimes with a short "climb high, sleep low" activity.
These days can make the difference between rushing through altitude and allowing your body to adapt progressively.
Do not try to maintain your normal sea-level walking speed.
At altitude, a slower and steady pace is often more sustainable.
Take appropriate breaks and avoid exhausting yourself early in the day.
A trek is not a competition.
Cold temperatures, dry mountain air, increased breathing, sweating, and physical exertion can all influence your fluid requirements.
Drink regularly and maintain adequate hydration.
However, drinking excessive amounts of water does not prevent altitude sickness and can itself create health risks.
The goal is adequate hydration, not overhydration.
Your body needs energy both for trekking and for the physiological process of acclimatization.
Even if your appetite decreases at altitude, try to maintain regular meals and snacks.
Carbohydrate-rich foods can provide a useful source of energy during strenuous trekking.
Alcohol can interfere with sleep and may contribute to dehydration.
Avoiding alcohol during the initial stages of acclimatization at high altitude is therefore a sensible precaution.
Do not ignore symptoms such as:
Headache
Nausea
Dizziness
Unusual fatigue
Loss of appetite
Difficulty walking
Increasing breathlessness
These may be altitude sickness symptoms, particularly when they appear after a rapid ascent.
Tell your trek leader or guide rather than hiding symptoms.
This is one of the most important rules of altitude safety:
If your symptoms are getting worse, do not go higher.
Reaching a summit is never more important than your health.
If a trekker develops serious altitude-related symptoms, descent may be necessary even if it means abandoning the planned itinerary.
One of the most common misconceptions about high altitude trekking is that physical fitness automatically protects you from altitude sickness.
It doesn't.
Fitness and acclimatization are two different things.
Being physically fit can certainly help you handle the demands of a difficult trek. Good cardiovascular endurance, strong legs, a strong core, and good overall conditioning can make long days of walking with a backpack more manageable.
However, physical fitness does not make you immune to acute mountain sickness.
A highly trained athlete can develop AMS, while a moderately fit trekker may acclimatize successfully.
This is because altitude sickness is influenced by factors such as:
Rate of ascent
Sleeping altitude
Individual susceptibility
Previous altitude exposure
Time allowed for acclimatization
Previous experience at altitude may provide useful information about how your body responds, but it is not a guarantee of future immunity.
Physical preparation should focus on helping your body handle prolonged exertion.
Walking, jogging, cycling, swimming, stair climbing, and other aerobic activities can help improve endurance.
Squats, lunges, step-ups, and controlled uphill training can help prepare your legs for long climbs and descents.
A strong core can help with balance, posture, and carrying a trekking backpack over uneven terrain.
Before your trek, practise walking for longer durations and gradually introduce a backpack with an appropriate load.
Stair climbing and uphill walking can help prepare your body for sustained elevation gain.
Training every day without sufficient recovery can leave you fatigued before your trek even begins.
Rest, sleep, nutrition, and recovery are part of preparation.
The easiest way to remember the difference is:
Fitness prepares you for the physical work.
Acclimatization prepares your body for reduced oxygen availability.
You need both for a safer and more enjoyable high altitude trek.
Even excellent physical preparation cannot replace a gradual ascent and proper high altitude acclimatization.
Ultimately, successful high-altitude trekking depends on a combination of fitness, preparation, gradual ascent, adequate acclimatization, sensible hydration and nutrition, awareness of altitude sickness symptoms, and the willingness to descend when your body tells you that something is wrong.
The mountain does not reward the person who ignores their limits. It rewards the person who respects them.
High-altitude trekking is not just about reaching a summit or ticking a destination off your list. When you are trekking thousands of metres above sea level, planning, acclimatization, safety, and experienced guidance matter just as much as the trail itself.
At Thin Air Expedition, we believe that a successful trek is one where you challenge yourself while respecting what your body needs at altitude.
Altitude can be unpredictable, which is why responsible trekking requires more than simply following a route. Our approach focuses on sensible ascent schedules, acclimatization, monitoring trekkers, and responding appropriately when someone is struggling with altitude.
We believe that no summit is more important than a trekker's safety.
A high-altitude trek should give your body enough time to adapt to reduced oxygen availability.
Our itineraries are planned with altitude gain, sleeping altitude, rest, and acclimatization in mind rather than focusing only on covering maximum distance each day.
The mountains demand awareness and experience. Our team understands the changing conditions of Himalayan terrain and the challenges that can arise during high-altitude trekking.
From pacing yourself on steep ascents to recognizing when your body may be struggling, experienced guidance can make a significant difference.
We don't see trekking simply as reaching a campsite, pass, or summit.
For us, it is about experiencing the mountains responsibly, understanding the terrain, respecting local environments, and returning with memories that last much longer than the achievement itself.
Whether you are preparing for your first Himalayan trek or planning a more demanding high-altitude adventure, Thin Air Expedition aims to make the journey as meaningful as the destination.
Prepare well. Acclimatize wisely. Trek responsibly. And let the mountains set the pace.
If you're planning a high-altitude trek in the Himalayas, choose an itinerary that respects your body, the terrain, and the altitude.
Explore your next Himalayan adventure with Thin Air Expedition.
