Related Clues

• 0, in some measures
• The Caspian is just below it
• Denver is way above it
• Death Valley is below it
• Zero altitude
• Average height of the ocean's water
• Altitude baseline
• Where many geographical measurements begin
• It's affected by global warming
• Land formation measuring standard
• 0 on an altimeter
• Where the buoys are
• Mean position between tides
• It rises every year
• High ground is above it
• Standard for measuring map heights
• From which the heights of hills etc are measured
• Rising concern?
• Elevation standard
• At this point, land appears