Mean sea level is defined as?

Mean sea level is defined as the average height of the sea surface over a 19-year period because this time frame accounts for the variations caused by tides, weather, and other factors. This extensive averaging helps in mitigating the effects of seasonal and short-term fluctuations, providing a stable reference point used in navigation and charting. By incorporating a 19-year span, it captures the long-term trends and cyclic patterns of sea surface levels, allowing for a consistent standard across various geographical areas.

This information is critical for maritime navigation, as understanding mean sea level helps in charting safe navigation routes and in the construction of coastal infrastructure.