Places artificially created such as tunnels, mines, basements, and dug holes, or places under water, or existing temporarily as a result of ebbing of sea tide etc., are not included.
Fully natural places below sea level require a dry climate; otherwise, rain would exceed evaporation and fill the area.
All figures are in meters below mean sea level (as locally defined), arranged by depth, lowest first: Deeper and larger than any of the trenches in the list above is the Bentley Subglacial Trench in Antarctica, at a depth of 2,540 m (8,330 ft).
It is subglacial, covered permanently by the largest glacier in the world.
The biggest dry land area below sea level that has been known to exist during the geological past, as measured by continuous volume of atmospheric air below sea level, was the dry bed of the Mediterranean Sea of the late Miocene period during the Messinian salinity crisis.