Measuring Heights
Mountain peaks are measured from the sea level. Suppose a mountain is in the sea, the part of it which lies below the sea isn’t added to it’s height. So a mountain lying in the sea says, “unfair!”
Measuring sea level in turn is another complex problem because the sea isn’t at the same level everywhere. In fact, the sea level is much higher at the base of a mountain because the mountain’s mass increases the gravity and pulls the sea water making it higher there. Even if there isn’t any sea around mount Everest, the calculated sea level (higher than normal) is used as the base of the mountain. From this raised sea level to the peak, Mt. Everest measures 8,848 m.
This is how sea level is calculated: