In a nautical term - "mean sea level" is defined for a body of H20?

Question

What I have been able to find, Nothing defines, what body of H20 oceans/ lakes 'just has the defination for 'mean sea level' - WHAT would be the 'MEAN SEA LEVEL' for all the oceans of the World? EX: Panama Canal difference between Atlantic and Pacific ocean

Answer 1

Mean sea level is a average of all stages of a tide at a particular location. There are many stages of tide; mean higher high, mean high springs, mean high water, mean high water neaps, mean lower low water, mean low water. Mean lower water is the datum for nautical charts. Local tides vary due to local geographic formations and lunar effects.

The moon does not affect the water level of lakes since the amount of water is fixed. Large lakes usually have high volume free flowing sources of water that may add or substract a noticeable quantity which may influenced by the moon.

Answer 2

MSL is defined as the zero elevation for a local area. The zero surface referenced by elevation is called a vertical datum. Unfortunately for mapmakers, sea level is not a simple surface. Since the sea surface conforms to the earth's gravitational field, MSL also has slight hills and valleys that are similar to the land surface but much smoother. However, zero elevation as defined by Spain is not the same zero elevation defined by Canada, which is why locally defined vertical datums differ from each other.

The MSL surface is in a state of gravitational equilibrium. It can be regarded as extending under the continents and is a close approximation of the geoid. By definition, the geoid describes the irregular shape of the earth and is the true zero surface for measuring elevations. Because the geoid surface cannot be directly observed, heights above or below the geoid surface can't be directly measured and are inferred by making gravity measurements and modeling the surface mathematically. Previously, there was no way to accurately measure the geoid so it was roughly approximated by MSL. Although for practical purposes, at the coastline the geoid and MSL surfaces are assumed to be essentially the same, at some spots the geoid can actually differ from MSL by several meters.

***More info available in my sources***

Answer 3

the 'MEAN SEA LEVEL' for all the oceans of the World is 0