The Ocean Environment was explored to determine the effects of temperature, absorption and leakage on acoustic propagation. Having modeled the acoustic region, a cylindrical sonar is evaluated to determine its array gain as a function of frequency. The Detection Threshold is analyzed and its impact on signal detectability discussed in detail. utilizing the Passive Sonar Equation, the sonar's effectiveness is quantitatively measured as a function of frequency for a typical noise source. Correlation techniques, modeled on an IBM PC, are then introduced to improve the sonar's effectiveness.