metres
yards or meters
a centimeter
Kilometers
Its height (above mean sea level): metres Its length: kilometres - or metres if it is a really short trail.
That depends what you want to measure: its height, its mass, its color, its temperature, etc.
Feet.
A millimetre.
Centimetres.
Metres.
You would use meters.
I would use meters.
yards or meters
Metre
meters
Feet
Metre or foot and inches
a centimeter