What is Sea Level?

Sea levels change with the rise and fall of tides.
The Dead Sea lies 1371 feet below sea level.
California's Death Valley is 282 feet below sea level.
A map of the polar ice caps, which can cause the sea level to rise if they melt.
Mt. Everest is almost 30,000 feet above sea level.
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  • Written By: Phil Shepley
  • Edited By: Bronwyn Harris
  • Images By: Iko, Victor B, Paul Lemke, Lunar And Planetary Institute, Qiangba Danzhen
  • Last Modified Date: 26 May 2015
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Sea level, also referred to as mean sea level, is the level at which the oceans exist when averaged between high and low tides. It is calculated by measuring the level of the ocean over extended periods of time and under all types of weather conditions. The mean is used by geographers to calculate the height or depth of any point of the Earth’s land surface, for instance the height of Mount Everest is considered to be 29,028 feet (8,848 meters) above sea level.

The actual level of the sea is constantly changing as tides rise and fall, and as surrounding winds and currents change. Other factors that cause changes include water temperature, air pressure, season of the year, the presence of ice and snow, and the amount of salt in the water. All of these widely varying factors can be completely different from place to place, therefore sea level can vary depending on where it is being measured in the world, and it is not a constant.


Mechanical tide gauges are just a small part of the complicated process that is used to determine the measurement of mean sea level. These devices measure the average height of the sea with respect to the land over a period of time, which means a change in the height of the land can also affect the measurement of the sea. They can be used independently to calculate the mean sea level of a specific location, or many tide gauges can be used simultaneously to determine the level of a large body of water.

The measurement of mean sea level has many uses. One of these is for aviation, where it is often crucial for a pilot to be able to determine his or her height above this level at any given time. Another important function of is to determine how much the sea is rising due to factors such as the melting of the polar ice caps. Mostly, it is calculated in order to determine heights of geological formations and land.

While most of the land in the world lies above sea level, there are still several places that actually exist below it. Death Valley, California, for instance, is 282 feet (85.5 meters) below sea level, and there are many other similar locations throughout the world. The Dead Sea is the lowest of these, measuring an amazing 1371 feet (418 meters) below sea level.


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Post 3

what are the reasons why Tuguegarao City is the hottest place in the Philippines? where is the reference to sea level?

Post 2

Cebu City lies at about 2950 feet above mean sea level.

On a side note, I have heard that Cebu City is a beautiful place. I grew up with a girl in Hawaii, and her parents were originally from the Philippines. Her grandparents still live in the Philippines, and they are from some island just off the coast of Cebu City. I recognized Cebu City, so I took the opportunity to research your question.

Post 1

how much is the correct sea level measurement here in cebu city philippines?

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