That type of map is called a thematic.
a red line
A map key is made up of symbols used to make a map easier to read
A map of the ocean is called a topographic map. On a map the oceans surface has highs and lows look similar to the hills and valleys of the Earth's surface.
Google Maps, Yahoo! Maps and British Ordinance Survey maps use a mid-blue colour for all water features (rivers, streams, lakes and the sea).
Green is typically used to represent forests on an OS (Ordnance Survey) map. It helps observers easily identify wooded areas as they navigate through the map.
sonar,is used to map mid-ocean ridges:]
thematic
blue'
Scientist use Sonar to map the ocean floor. Scientist use Sonar to map the ocean floor.
the color blue on a map often shows a lake or an ocean = D
A current map, or ocean current map, would be used to depict the speed and direction of ocean currents. These maps illustrate the movement of surface ocean water across regions and are important for understanding ocean circulation patterns.
Sonar.
sonar
Sonar.
green
Four colours are used to colour a map or pattern so that no colour is next to the same colour.