SONAR

Although they rely on two fundamentally different types of wave transmission, SONAR and Radio Detection And Ranging (RADAR) and both are remote sensing systems. Whilst active SONAR transmits acoustic (i.e., sound) waves, RADAR sends out and measure the return of electromagnetic waves,

Both systems these waves return echoes from certain features or targets that allow the determination of important properties or attributes of the target (e.g., shape, size, speed, distance to target, etc.). Because electromagnetic waves are strongly attenuated (diminished) in water, RADAR signals are mostly used for ground or atmospheric observations. Because SONAR signals easily penetrate water, they are ideal for naviagtion and measurement under water.