Would you ever go bungee jumping? How about parachuting out of an airplane? Maybe you’d like to try out a human catapult. These forms of recreation are thrilling for some. Others find them scary. If you’re looking for a sport with a bit of danger, you may enjoy mountain climbing.

Specifically, some thrill-seeking mountain climbers tackle the challenge of climbing Mount Everest. At 29,029 feet (8,848 meters) above sea level, it’s the highest mountain in the world. The first people to reach its summit were Sir Edmund Hillary and Tenzing Norgay in 1953. Since then, over 4,000 people have reached the mountain’s peak.

To do so, climbers must enter the most dangerous part of the mountain. It’s called the “death zone.” To prepare, climbers must give their bodies time to get used to higher altitude. That’s why they normally spend several weeks climbing Mount Everest. They stop to rest every few thousand feet. When they reach 26,247 feet (8,000 meters), they’ve entered the death zone.

How dangerous is the death zone? That far above sea level, the amount of oxygen in the atmosphere falls 40 percent. This makes it difficult for the human body to get the oxygen it needs. Combined with the physical exertion of climbing the mountain, this can be deadly. Some climbers have compared the experience to “running on a treadmill and breathing through a straw.”

Every cell in your body needs oxygen to carry out its job. For that reason, the low-oxygen nature of the death zone makes it a very dangerous place. It can have dire effects on the human body. 

One of these is swelling of the brain. This may lead to high altitude cerebral edema (HACE). HACE can cause nausea and vomiting. Even more dangerous, it can lead to difficulty thinking. In the death zone, climbers can forget where they are or even have hallucinations. This can make a dangerous climb even more life-threatening.

Many climbers experience high altitude pulmonary edema (HAPE) in the death zone. Symptoms of HAPE include fluid in the lungs, fatigue, and weakness. Climbers affected by HAPE can also feel like they’re suffocating. They will have a persistent cough. They may cough up white, frothy fluid.

Other dangers posed by the death zone are snow blindness and frostbite. Snow blindness is the temporary inability to see due to the glare from snow and ice. Frostbite can affect any exposed skin. The temperatures on Mount Everest are low enough to freeze skin instantly.

Mount Everest isn’t the only peak with a death zone. In fact, the world’s 14 highest mountains all have death zones. All of these are located in the Himalaya and Karakoram Ranges on the continent of Asia. Some avid mountain climbers make it their goal to reach the top of all 14.

Would you like to climb Mount Everest one day? How would you protect yourself from the death zone? Mountain climbing requires both skill and preparation. If you’re interested in this sport, spend some time learning about the important safety precautions today.