Mean Sea Level (MSL) is the average height of the ocean's surface, measured over a long period, typically 19 years. It serves as a baseline for determining elevations and depths on land and in water. MSL is influenced by various factors, including tides, atmospheric pressure, and ocean currents. Scientists use MSL as a reference point for mapping and navigation. It helps in understanding changes in sea levels due to climate change and other environmental factors. Accurate measurements of MSL are crucial for coastal planning and managing the impacts of rising sea levels on communities and ecosystems.