Abstract: A liquid crystal display depth finder using a sonar transducer is provided with a plurality of input keys interfaced to a microprocessor with each input key being dedicated to a particular function or feature usable with the depth finder. The microprocessor is utilized to control the operation of the transducer and the display of the data generated thereby in accordance with the particular function or set of functions chosen by the operator and to manipulate programming stored within the depth finder which will enable a tutorial mode comprising alphanumeric information and command key indication such that an the user may determine how the machine is to properly function.