Like water in the ocean, air in the atmosphere exerts pressure that increases with depth. Most gas molecules in the atmosphere are pulled close to Earth’s surface by gravity. As a result, air pressure decreases quickly at lower altitudes and then more slowly at higher altitudes. This is illustrated in Figure below . Air pressure is greatest at sea level, where the depth of the atmosphere is greatest. At higher altitudes, the pressure is less because the depth of the atmosphere is less. For example, on top of Mount Everest, the tallest mountain on Earth, air pressure is only about one-third of the pressure at sea level. At such high altitudes, low air pressure makes it hard to breathe and is dangerous to human health.
Mat loved being outside and being physically active. So he took every opportunity to go mountain climbing. Last year he went on two climbs. The first A was challenging but lots of fun. On his second climb B he had some trouble though. Near the top of the mountain he was having trouble breathing he got very light headed and was not able to continue.
Which mountain is highest from sea level?