Park rangers who watch North America’s highest mountain say inexperienced and overconfident climbers are taking more risks and endangering themselves and other climbers. The rangers suggest many climbers are trying to move up the mountain too fast after having a year off because of the COVID-19 pandemic. Denali in southern Alaska is 6,190 meters (20,310 feet) above sea level. So, climbing it requires a high level of skill. Climbers also need to acclimate to high altitudes that is not needed for most mountains in the U.S. Acclimation to high altitudes means you slowly permit your body to adapt, or get used to conditions. If you don’t, you could feel sick. Experts at America’s Cleveland Clinic say altitude sickness “happens when your body is unable to adapt to a low-pressure, low-oxygen environment…” This generally happens at about 2,400 meters (8,000 feet) above sea level. The National Park Service recently issued a statement warning that many climbers in the Alaska Range are showing signs of inexperience and overconfidence. After reporting no deaths in 2018 and 2019, at least two people have already died on the mountain in 2021. Two others were seriously injured, officials said. Earlier this month, a skier from the state of Colorado died after falling into a crevasse, or very deep cut in the ice. Rangers also reported that a climber from the state of Idaho was killed by a large falling piece of ice. The rangers issued their statement after a Canadian climber was seriously injured after falling nearly 305 meters (1,000 feet). He was not wearing climbing ropes. Other climbers reported the fall. People in a helicopter studying mountain ice in the area were able to rescue the man, park officials said.