Measure Between High and Low Tides

This page is the CodyCross answer for the clue below from Art Museum, Group 724, Puzzle 5 (Wooden Frames).

Question is: Measure Between High and Low Tides

and the answer is: SEALEVEL

Word Meaning:

SEA LEVEL — The nominal height of the surface of the oceans above which heights of geographical features and aircraft flight levels are measured.

Definitions from Wiktionary.