Everest Crowding & the Hillary Step
Bottleneck zones, the May 2024 cornice collapse, the oxygen math that decides who summits and who descends safely, and the 2026 dual fixed-line regulation reshaping the queue. Above 8,700 meters, standing still is as dangerous as climbing.
🔍 Five Frameworks for Understanding Everest Crowding
1. The compressed weather window driver. The viable summit window is typically just 5-10 days in May, and all commercial teams use the same forecast providers — forcing hundreds of climbers into the same 24-36 hour summit attempt.
2. The standing-still-kills physics. Above 8,700 meters in the death zone, every minute of queue delay depletes oxygen, drops core temperature, and impairs cognition — at the altitude where the body is already failing.
3. The 2015 earthquake transformation. The original 12-meter Hillary Step rock face was restructured by the April 2015 Nepal earthquake into a 45-60 degree snow slope with unstable cornice — different terrain, different (still dangerous) hazards.
4. The crowding-event causation. The May 22, 2024 cornice collapse that killed four climbers was caused by queue weight overloading a cornice, not weather — making it a planning failure, not a force of nature.
5. The descent oxygen math. Descent is 30-50% slower than ascent. A queue that consumes 37-50% of cylinder supply at 3 L/min summit flow can leave climbers without enough oxygen to descend safely.
Mount Everest crowding refers to the documented safety hazard created when hundreds of climbers attempt to summit within the same 24-36 hour weather window, producing queues of 90-120 minutes at narrow terrain features above 8,700 meters elevation. Generally, the most critical bottleneck is the Hillary Step area on the South Col route, where the May 2024 cornice collapse killed four climbers under the weight of a long queue. Specifically, Everest crowding is no longer a logistical inconvenience but a documented contributor to death zone fatalities — the 2019 season saw 4-11 deaths attributed to queue exposure, and the 2024 cornice incident drove Nepal’s 2026 dual fixed-line regulation. Notably, the North Col (Tibet) route sees significantly fewer climbers (100-200 per season versus 600-900+ on the South side) due to Tibet’s enforced 300-permit cap.
Key Takeaways
- Spring 2025 saw 851 successful summits — the third-busiest Everest season on record, with crowding patterns continuing intense.
- Spring 2024 saw approximately 900 climbers on the slopes — the highest single-season population ever recorded at that point.
- The Hillary Step is now a 45-60 degree snow slope following the April 2015 Nepal earthquake (7.8 magnitude), not the original 12-meter rock face.
- The May 22, 2024 cornice collapse killed four climbers — Daniel Paul Paterson (UK), Pastenji Sherpa (Nepal), Cheruiyot Kirui (Kenya), Nawang Sherpa (Nepal).
- Queue duration of 90-120 minutes is now routine at the South Summit to Hillary Step section during peak summit windows.
- A 90-minute queue at 3 L/min flow consumes 37-50% of oxygen supply — leaving inadequate reserves for the 30-50% slower descent.
- The North Col (Tibet) route sees 100-200 climbers per season versus 600-900+ on the Nepal South side, due to Tibet’s 300-permit cap.
- Nepal’s 2026 regulations mandate dual fixed lines (separate ascent and descent ropes) through the Hillary Step area following the 2024 collapse.
- Five primary bottleneck zones structure the South Col route — Khumbu Icefall, Lhotse Face, South Col to Balcony, South Summit to Hillary Step, Cornice Traverse.
The Scale of the Problem
Overcrowding on Mount Everest has transformed from a logistical inconvenience into a documented safety hazard. Generally, the entire viable summit window is typically just 5-10 days in May, forcing hundreds of climbers to attempt the summit simultaneously. Specifically, all commercially-guided teams receive weather forecasts from the same providers (Marc De Keyser, Chris Tomer, and a handful of others dominate Himalayan expedition forecasting) and tend to target the same 24-36 hour window, producing the queue dynamics that make crowding lethal at altitude.
The spring 2025 season produced 851 successful summits — the third-busiest Everest season on record. Spring 2024 saw approximately 900 climbers on Everest’s slopes, the highest single-season population ever recorded at that point. Notably, 2019’s short weather window forced queues at the Hillary Step area that contributed to at least 4-11 deaths from exhaustion, oxygen depletion, and exposure. The crowding-fatality correlation is no longer theoretical.
Above 8,000 meters, standing still is as dangerous as climbing. A 90-minute queue at the Hillary Step depletes supplemental oxygen, drops core temperature, and impairs cognitive function — all at the altitude where the body is already failing. Every minute of delay in the death zone has a measurable physiological cost. The queue itself is the hazard, separate from any weather or terrain risk.
The Five Primary Bottleneck Zones on the South Col Route
The South Col route from Nepal has five distinct choke points where traffic can stall. Generally, each bottleneck has a different character, altitude, and level of risk. Specifically, climbers should understand all five before committing to a South side expedition — pre-trip awareness drives summit-day decisions that determine survival.
1. Khumbu Icefall
Shifting seracs and crevasses force climbers through a single route maintained by the Icefall Doctors. Ladder crossings can queue 15-30 minutes. Generally, the Icefall has the highest objective hazard of any bottleneck zone — falling ice, collapsing seracs, and crevasse danger are all weather-independent risks. Specifically, the Icefall is most-dangerous in the afternoon when sun warms the ice; climbers traverse pre-dawn during acclimatization rotations.
2. Lhotse Face
Steep blue ice with a single fixed-rope line running the full 900 m height gain. Generally, overtaking another climber is nearly impossible on the Lhotse Face — the entire face is one queue. Specifically, slowdowns propagate the entire length of the face, often forcing climbers to wait in jumar position with no shelter from wind. The Lhotse Face is where stamina differences between climbers create the first significant separation.
3. South Col to Balcony
Night-time start congestion. All teams depart Camp 4 targeting the same summit window — typically 12am-2am. Generally, the first two hours above the Col can become a slow procession of headlamps stretching upward. Specifically, this is the climber’s first sustained exposure to the death zone, with crowd dynamics compounding altitude effects. Slower climbers should leave earlier to avoid being caught in the main wave.
4. South Summit to Hillary Step
Extreme terrain narrowing — only one climber can pass at a time. This is where 90-120 minute queues have been documented. Generally, all delay here occurs above 8,700 meters in the death zone — the most physiologically expensive bottleneck. Specifically, the section has the worst altitude-to-queue-duration ratio on the entire route. This is the bottleneck that defines Everest crowding as a safety issue.
5. Cornice Traverse
A knife-edge snow ridge between the Hillary Step and the summit. Any slowdown causes a full-column backup. Generally, this is the location of the May 22, 2024 cornice collapse that killed or disappeared four climbers. Specifically, the cornice overhanging the Kangshung Face was loaded beyond stability by the weight of a long queue of climbers — the collapse was a crowding event, not a weather event.
Following the 2024 Hillary Step cornice incident, Nepal’s 2026 regulations now mandate separate ascent and descent fixed ropes through the Hillary Step area and adjacent Cornice Traverse. Generally, this reduces head-on traffic conflict and improves throughput at the critical bottleneck. Specifically, it does not eliminate the underlying altitude hazard — climbers still wait in position above 8,700 m, just with reduced rope-conflict delays. Notably, the regulation works in combination with mandatory GPS tracking and RECCO reflectors (also new for 2026) to support rescue and recovery operations if another cornice event occurs.
The Hillary Step: Then, Now, and 2026
What It Was Before 2015
The original Hillary Step was a 12-meter near-vertical rock and ice face at approximately 8,790 meters — the final serious technical obstacle before the summit. Generally, it required genuine rock climbing technique and forced climbers into single file because the feature could only be negotiated one person at a time. Specifically, the section was named for Sir Edmund Hillary, who first climbed it (along with Tenzing Norgay) during the 1953 first ascent of Everest. For 62 years between 1953 and 2015, the Hillary Step was the most-photographed technical feature on Everest and the single most-defining obstacle of the South Col route.
What the 2015 Earthquake Changed
The April 25, 2015 Nepal earthquake (magnitude 7.8) restructured the terrain at the Step. Generally, post-2015 reports and photographs from the first climbers to summit Everest after the earthquake (2016 season) showed dramatically different terrain. Specifically, what had been a defined rock face was transformed into a mixed snow, ice, and debris slope. The current consensus among expedition operators and climbers who have summited since 2016: the rock step is gone or deeply buried under snow and debris. Notably, the change was controversial at first — climbers debated whether the rock might be exposed in subsequent low-snow years — but consistent reports from 2017-2025 confirm the rock step is no longer present as a discrete climbing obstacle.
2026 Status
What remains at 8,790 meters today is a steep snow slope with significantly different character from the historical Hillary Step. Generally, the terrain is a 45-60 degree snow slope with loose debris and an unstable cornice above the Kangshung Face — still difficult, still dangerous, but differently so. Specifically, the 2026 status includes:
- Terrain: 45-60 degree snow slope with loose debris
- Cornice hazard: Unstable cornice above the Kangshung Face (site of 2024 collapse)
- Queue duration: 90-120 minutes documented during peak summit windows in 2024 and 2025
- Fixed lines: Dual fixed lines (separate ascent and descent ropes) now required under 2026 regulations
- Tracking: GPS tracking and RECCO reflectors mandatory — partly to assist recovery if another cornice event occurs
- Monitoring: Government rangers monitor route conditions throughout the season
Notably, the elimination of the technical rock crux has not reduced the danger of the section — it has shifted the danger from technical climbing difficulty to crowd-driven cornice instability and oxygen-depletion queue exposure. The Hillary Step kills differently in 2026 than it did in 1996, but it still kills.
The May 22, 2024 Cornice Collapse
On May 22, 2024, a soft cornice overhanging the Kangshung Face near the Hillary Step collapsed under the weight of a long queue of climbers. Generally, several climbers fell during the collapse but were stopped by fixed ropes. Specifically, four climbers died or disappeared in the incident:
| Climber | Age | Nationality | Outcome |
|---|---|---|---|
| Daniel Paul Paterson | 40 | British | Fell in collapse; body never recovered |
| Pastenji Sherpa | 23 | Nepali | Fell in collapse; body never recovered |
| Cheruiyot Kirui | — | Kenyan | Missing from same incident; search abandoned |
| Nawang Sherpa | 44 | Nepali | Missing from same incident; search abandoned |
The collapse was directly linked to the weight of a long summit queue overloading a cornice at a narrow section. This was not a weather event — it was a crowding event. Generally, the incident drove Nepal’s 2026 dual fixed-line requirement and reinforced the government push for GPS monitoring of all climbers above Base Camp. Specifically, the cornice had been considered stable in previous seasons; the variable that changed was queue duration and the number of climbers concentrated on the narrow section at one time. Notably, this means similar incidents remain possible at other narrow sections of any high-altitude route where crowds can concentrate weight on snow features above significant drops.
The Oxygen Math That Decides Survival
Most Everest climbers use supplemental oxygen above Camp 3 or Camp 4. Generally, understanding exactly how a queue depletes your supply is one of the most critical pieces of safety planning you can do before summit day. Specifically, the math is unforgiving — flow rates that feel necessary for active climbing become dangerous when applied to standing still in a queue.
| Flow Rate | Cylinder Duration | 90-Min Queue Cost | Risk Level |
|---|---|---|---|
| 1 L/min — sleeping | 7-9 hours | ~17% of supply | Low |
| 2 L/min — climbing | 5-7 hours | ~21-25% of supply | Moderate |
| 3 L/min — summit push | 3-4 hours | 37-50% of supply | High |
| 4 L/min — emergency | 2.5-3 hours | Any significant queue potentially fatal | Critical |
Climbing speed on the descent is typically 30-50% lower than on ascent. Generally, a climber who depletes half their oxygen waiting in a queue at the Hillary Step may not have enough supply to descend safely. Specifically, the queue does not only affect your summit bid — it affects your survival on the way down. Notably, this is why experienced guides consistently recommend turning around when long queues form: not because the summit becomes impossible, but because the descent becomes survival-marginal.
The North Side Option (Tibet)
The Tibet (North Col) route sees significantly fewer climbers than the Nepal south side and offers a meaningfully different crowd profile for climbers who can access it. Generally, the North side is the structural answer to South side crowding — at the cost of more complex access and different (but real) hazards.
| Factor | South Side (Nepal) | North Side (Tibet) |
|---|---|---|
| Annual permit cap | No formal cap (300-400+ teams historically) | ~300 permits (enforced) |
| Typical climbers per season | 600-900+ | 100-200 |
| Client-to-Sherpa ratio (2025) | 1.4:1 | 0.76:1 |
| Main technical crux | Hillary Step / Cornice Traverse (8,790 m) | Second Step at 8,611 m (fixed ladder) |
| Base camp access | Trek from Lukla (~10-14 days) | Vehicle access — simpler logistics |
| Access reliability | Stable — consistent permit process | Variable — Tibet border rules can change |
| 2024 cornice incident exposure | Direct (5 deaths/missing) | None (different terrain) |
For climbers who qualify and can navigate Tibet access requirements, the north side reduces bottleneck exposure significantly. Generally, the route has its own serious hazards — higher winds, more exposed high camps, more technical terrain above 8,000 m, and the Second Step bottleneck at the fixed ladder. Specifically, queue-related death zone delays are far less common on the North side, but objective hazards (rockfall, wind exposure, technical difficulty) are higher. Notably, Tibet access requirements can change without warning — political dynamics between China and individual climbers’ home countries can result in permit denial — making the North side less reliable to plan despite its lower crowds.
Tactical Advice: Managing the Crowds
Experienced climbers and guides have developed consistent strategies for navigating the crowding problem. Generally, these are not comfort measures — they are safety measures grounded in repeated exposure to crowded summit windows. Specifically, the four-component framework below structures pre-trip planning and summit-day decision-making.
🕐 Timing Strategy
- Leave Camp 4 earlier than most teams — being 30-60 minutes ahead of the main wave significantly reduces queue time.
- Monitor what other operators are doing; if all teams depart simultaneously, you will queue.
- In 2025, teams that waited for the secondary May 18-19 window faced fewer climbers than the first wave.
- Consider targeting the second weather window of the season rather than the first and busiest.
🎯 Decision Protocol
- Agree in advance with your guide on turnaround criteria — time, oxygen level, and physical state.
- Commit to those criteria before leaving Camp 4, not while standing in a queue at 8,700 m.
- If a queue forms and your oxygen reserve drops below the pre-agreed threshold: descend.
- Experienced guides say the correct answer to a 90-minute queue at the Hillary Step is almost always: turn around.
🤝 Operator Selection
- Ask: “What do you do when there’s a queue at the Hillary Step?”
- Operators willing to skip or delay a summit window due to crowds are demonstrably safer.
- 2024 and 2025 data confirms operators who waited for calmer conditions had stronger safety records.
- A lower-cost operator may lack the experience or flexibility to hold clients back from a dangerous queue.
🫁 Oxygen Planning
- Carry at least one more cylinder than your operator’s standard allocation.
- Agree with your Sherpa on a specific oxygen level at which you turn around — non-negotiable.
- Know your flow rate, cylinder capacity, and estimated descent time before leaving Camp 4.
- Extra cylinders cached at the South Summit are standard in premium expeditions — ask if yours does this.
The best expedition outcomes from 2025 ended not at the summit, but with safe descents, good decision-making, and enough oxygen margin to get home. Generally, Everest rewards strong climbs, but punishes climbers who treat the summit as the endpoint rather than the halfway point. Specifically, every minute of queue time makes the descent more dangerous — plan accordingly. Notably, the climbers who survived 2024’s cornice collapse were those who had already turned around before reaching the queue, or those whose operators committed to second weather windows rather than fighting through first-window crowds.
Frequently Asked Questions
Why has Everest crowding gotten worse in recent years?
Everest crowding has worsened due to a combination of factors that compress hundreds of climbers into the same narrow summit window. The viable summit window is typically just 5-10 days in May, and all commercially-guided teams receive weather forecasts from the same providers and tend to target the same 24-36 hour window. In spring 2024 approximately 900 climbers were on Everest’s slopes — the highest number ever recorded at that point. Spring 2025 saw an estimated 851 climbers summit successfully, making it the third-busiest season on record. The combination of higher permit issuance from Nepal’s Department of Tourism (no formal cap on south side permits, unlike the 300-permit Tibet north side cap), growing global interest in eight-thousander climbing, and the shared weather window dynamic produces routine queues at Hillary Step lasting 90-120 minutes during peak summit days. The queue itself becomes a safety hazard above 8,700 meters where standing still consumes oxygen and drops core temperature, making delay physiologically dangerous.
What was the Hillary Step originally, and what happened to it?
The Hillary Step was originally a 12-meter near-vertical rock and ice face at approximately 8,790 meters elevation — the final serious technical obstacle before the Everest summit on the South Col route. It required genuine rock climbing technique and forced climbers into single file because the feature could only be negotiated one person at a time. The April 25, 2015 Nepal earthquake (magnitude 7.8) restructured the terrain at the Step. Post-2015 reports and photographs showed what had been a defined rock face transformed into a mixed snow, ice, and debris slope. The current consensus among expedition operators and climbers who have summited since 2015 is that the rock step is gone or deeply buried under snow and debris. What remains is a steep 45-60 degree snow slope with loose debris and an unstable cornice above the Kangshung Face — still difficult, still dangerous, but differently so. The elimination of the technical rock crux means more climbers can attempt the section, contributing to higher traffic volume and longer queues at this altitude.
What happened in the May 22, 2024 Hillary Step cornice collapse?
On May 22, 2024, a soft cornice overhanging the Kangshung Face near the Hillary Step collapsed under the weight of a long queue of climbers. This was a crowding event rather than a weather event. Four climbers died or disappeared: Daniel Paul Paterson (40, British) fell in the collapse and his body was never recovered; Pastenji Sherpa (23, Nepali) fell in the collapse and his body was never recovered; Cheruiyot Kirui (Kenyan) was reported missing from the same incident with search abandoned; and Nawang Sherpa (44, Nepali) was reported missing from the same incident with search abandoned. The collapse was directly linked to the weight of a long summit queue overloading a cornice at a narrow section. The incident drove Nepal’s 2026 dual fixed-line regulation requiring separate ascent and descent ropes through the Hillary Step area, and reinforced Nepal’s push for GPS monitoring of all climbers above Base Camp.
How much oxygen does a 90-minute queue at the Hillary Step consume?
A 90-minute queue at the Hillary Step consumes between 17% and 50% of a supplemental oxygen cylinder depending on flow rate. The lower the flow rate, the longer the cylinder lasts, but the harder physical activity becomes. At 1 L/min sleeping flow rate (7-9 hour cylinder duration), a 90-minute queue consumes approximately 17% of supply. At 2 L/min climbing flow rate (5-7 hour cylinder duration), a 90-minute queue consumes 21-25% of supply. At 3 L/min summit-push flow rate (3-4 hour cylinder duration), a 90-minute queue consumes 37-50% of supply — critical depletion. At 4 L/min emergency flow rate (2.5-3 hour cylinder duration), any significant queue is potentially fatal. Climbing speed on the descent is typically 30-50% lower than on ascent. A climber who depletes half their oxygen waiting in a queue at the Hillary Step may not have enough supply to descend safely. The queue does not only affect your summit bid — it affects your survival on the way down.
Is the North side route in Tibet less crowded than the South side?
Yes, the Tibet North Col route is significantly less crowded than the Nepal South Col route. The North side sees roughly 100-200 climbers per season versus 600-900 plus on the South side. Tibet enforces approximately 300 climbing permits per season as a formal cap, while Nepal has historically issued 300-400 plus permits with no formal annual cap. The 2025 client-to-Sherpa ratio was 1.4:1 on the South side versus 0.76:1 on the North side, reflecting both lower client volume and higher Sherpa support availability on the North. The main technical crux differs — South side features the Hillary Step and Cornice Traverse, North side features the Second Step at 8,611 meters which has a fixed aluminum ladder. The North side has its own serious hazards including higher winds, more exposed high camps, and more technical terrain above 8,000 meters — but queue-related death zone delays are significantly less common. North side access requires navigating Tibet border rules which can change without warning, making the route less reliable to plan despite its lower crowds.
What is the safest summit window timing strategy?
The safest summit window strategy is to target the second viable weather window of the season rather than the first and busiest. Climbers should monitor multiple weather forecast providers and what competing operators are planning. In 2025, teams that waited for the secondary May 18-19 window faced significantly fewer climbers than the first wave. The first weather window of the season typically draws maximum traffic because all teams have been waiting weeks at Base Camp and are eager to summit before the monsoon arrives. Subsequent windows often have similar weather quality with substantially lower crowd density. The strategy requires patience — operators committed to the first window may pressure clients to attempt despite known crowding. Verify your operator’s window flexibility before signing on. Additionally, leaving Camp 4 thirty to sixty minutes ahead of the main wave on any chosen day reduces queue exposure significantly compared to the main pack. Experienced climbers and guides have developed these strategies through repeated exposure to crowded windows — they are not comfort measures, they are safety measures.
Sources and Methodology
Sources
This page synthesizes data from official Nepal government sources, the Himalayan Database, news reporting from the 2019, 2024, and 2025 seasons, expedition operator post-season analyses, and cross-referenced firsthand climber accounts.
- Nepal Department of Tourism, Mountaineering Section. Official Mount Everest permit issuance, summit registration, and incident reporting authority. Source for spring 2025 summit counts (851), 2024 climber population (~900), and 2026 regulatory changes.
- Himalayan Database (Elizabeth Hawley, Billi Bierling). The definitive long-form record of Himalayan climbing history including Everest summit attempts, casualties, and route conditions since the 1953 first ascent.
- Reports from the 2024 Hillary Step cornice incident. Cross-referenced reporting from BBC News, The Himalayan Times, Reuters, and ExplorersWeb on the May 22, 2024 collapse and victim identification.
- Adventure Consultants, Alpine Ascents, IMG, and other premium operators. Post-season expedition reports and safety briefings from major commercial expedition companies operating on both Nepal and Tibet sides.
- NPR and The New York Times reporting on 2019 queue deaths. Coverage of the May 2019 Hillary Step queue that contributed to multiple deaths during a constrained weather window.
- Nepal’s 2026 mountaineering regulations. Department of Tourism announcements on dual fixed-line requirement, GPS tracking mandate, and RECCO reflector requirement effective 2026 season.
- Internal Global Summit Guide cross-references. See our companion analysis at Everest Safety & Fatality Statistics and Why Climbers Die on Everest Summit Day for related data.
- Supplemental oxygen consumption mathematics. Industry-standard cylinder capacity calculations cross-referenced with Summit Oxygen, Top Out Aero, and Poisk equipment specifications used by commercial Everest expeditions.
Methodology note. Quarterly review cycle — next review post-2026 spring Everest season (June 2026). Crowding patterns, queue durations, and regulatory environment change each season. Route conditions and bottleneck patterns are reviewed against expedition operator post-season reports and Nepal Department of Tourism announcements. Disclaimer: This page is for educational planning purposes only. It is not a substitute for qualified guiding, wilderness medicine training, or professional expedition risk management. Always verify current information with your expedition operator and the Nepal Department of Tourism (tourismdepartment.gov.np) before departure.
Continue the Everest Planning Series
Above 8,700 m, the Queue Is the Hazard
Generally, Everest crowding has transformed from logistical inconvenience to documented safety hazard. Specifically, the 2024 cornice collapse, 90-minute Hillary Step queues, and 37-50% oxygen depletion math all converge on a single conclusion: summit-day crowd management is now a survival skill, not a comfort consideration. Notably, the climbers who survive crowded windows are those who plan turnaround criteria before leaving Camp 4 and commit to them when queues form.
Read the Tactical Framework Everest Safety Stats →