This is the average level of the ocean over the entire earth. Tidal fluctuation is taken into account when determining sea level. Mean Sea Level (MSL) is used to reference the height of structures above ground level and depth below the ocean's surface. Atmospheric pressure is also referenced from sea level. At sea level, 760mm (29.92 inches) of mercury is normally displaced by the pressure of the air column above that point on the earth. [Nature; v367; p54-7; 1994.] [Environment; v36; p23-4; 1994.]
