Hypsometric Maps

http://www.reliefshading.com/colors/hypsometric.html

The image above is a picture of the Aegean Sea.  The map uses different shades of colors to show the relief (elevation) of the earths crust above and below sea level.  The colors only represent the relief of the land, for example the different shades of blue doesn't indicate warmer or cool water but instead how depth of certain areas in the Aegean sea.  The greenish/turquoise shades of color show the shelf of the shoreline surrounding the land that protrudes from the ocean.  The visible land in the map shows the terrain by using different shades of the color brown