Sea level rises and falls, so a datum line was put by the British Ordnance Survey on a harbour wall at Newlyn, Cornwall. It is from this datum line that mean sea level is measured.
i think it would be a no because sea level is the lowest level object
Altitude describes an object's position relative to sea level. An object in a position higher than sea level would have a positive altitude, sea level would have an altitude of zero, and any object below sea level would have a negative altitude.
If sea level is 0, then above sea level are positive elevations and below sea level are negative elevations.
110 metres above sea level
9.8′ above sea level
at sea level
Oxford is 129m above sea level
It is 781 feet above sea level.
It is 544 feet above sea level.
325 feet above sea level.
The object's mass is 3.57kg at sea level.
Part of it is at sea level. The highest point is 18.04 ft above sea level.