The polar waters are the saltiest in the world. The computer equipment is linked to satellites that translate coordinates of the submarine's exact position. Radar operates by using very high frequency radio waves reflected off of objects in the ocean to determine distance and direction of the object. Sonar detects the presence and location of submerged objects by bouncing sonic waves off of objects. Numerous instruments and methods are used to study all areas of the ocean for data on waves, tides, currents, sea water content, marine life, and bottom sediments.
Space technology offers a variety of data collection methods.
However, because of weather patterns, satellite images of oceanographic information are at times unclear. Surveys from ships are still the most widely used means of oceanographic data collection. Sometimes submarine vehicles and robots deployed from the ships are used for deep regions and better control of sampling. Tsunamis are long-period waves caused by an underwater distubance such as a submarine earthquake or volcanic eruption. These waves often travel great distances and, upon reaching shallow water, may build to heights of 50 feet or greater.