The level of the surface of the ocean; especially, the mean level halfway between high and low tide, used as a standard in reckoning land elevation or sea depths.
level of the ocean's surface esp that halfway between mean high and low tide; used as a standard in reckoning land elevation or sea depth
level of the ocean''s surface (especially that halfway between mean high and low tide); used as a standard in reckoning land elevation or sea depth
level of the ocean's surface (especially that halfway between mean high and low tide); used as a standard in reckoning land elevation or sea depth
