Tide gauge
Device for measuring the change in sea level relative to a datum / From Wikipedia, the free encyclopedia
A tide gauge is a device for measuring the change in sea level relative to a vertical datum.[citation needed] It is also known as a mareograph,[2] marigraph,[3] and sea-level recorder.[4] When applied to freshwater continental water bodies, the instrument may also be called a limnimeter.[5][6]
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Tidal_gauge_dsc06189.jpg/640px-Tidal_gauge_dsc06189.jpg)