SESK: Stuff Everyone Should Know · sesk.info/hike-altitude-8000-feet
At about what elevation does the Park Service warn hikers they risk altitude illness?
About 8,000 feet, where the air has less oxygen.
- 2,000 feet
- 8,000 feet ✔
- 20,000 feet
Why: Higher up, each breath brings in less oxygen. The Park Service warns that at 8,000 feet you are at risk of altitude illness, so take extra days to get used to the height, sleep well and drink water.
Huh, didn't know that: The CDC says about a quarter of visitors sleeping above 8,000 feet in Colorado get acute mountain sickness.
I tried to tell a joke at 8,000 feet, but it went over everyone's head.
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References
Answer: 8,000 feet. Higher up, each breath brings in less oxygen. The Park Service warns that at 8,000 feet you are at risk of altitude illness, so take extra days to get used to the height, sleep well and drink water.
- NPS: Hike Smart www.nps.gov/articles/hiking-safety.htm
Remember that at 8,000 feet you are at risk of altitude illness
Checked 2026-10-12. - CDC Yellow Book: High Altitude Travel and Altitude Illness www.cdc.gov/yellow-book/hcp/environmental-hazards-risks/high-altitude-travel-and-altitude-illness.html
affecting, for example, 25% of all visitors sleeping at altitudes >2,450 m (>8,000 ft) in Colorado.
Checked 2026-10-12.
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