Answer: sealevel

AnswerCrossword Clue
SEALEVEL

Standard reckoning in elevation

SEALEVEL

Altitude baseline

SEALEVEL

Where many geographical measurements begin

SEALEVEL
Zero altitude
SEALEVEL
Average height of the ocean's water
SEALEVELWhat many port cities are at
SEALEVELDeath Valley is below it
SEALEVELAltitudinal reference
SEALEVELStandard for height measurements.
SEALEVELStandard measure for height of land.
SEALEVELStandard for measurement of heights.
SEALEVELStandard for altitudes
SEALEVELStandard for measuring heights
SEALEVELAquatic plane
SEALEVEL0, in some measures
SEALEVELThe Caspian is just below it
SEALEVELDenver is way above it
SEALEVELIt's affected by global warming
SEALEVELPart of New Orleans is below it
SEALEVELLand formation measuring standard
SEALEVELHigh ground is above it
SEALEVEL0 on an altimeter
SEALEVELElevation standard
SEALEVELWhere the buoys are
SEALEVELCruising altitude?
SEALEVELIt rises every year
SEALEVELRising concern?
SEALEVELSomething on the rise today