Underwater searches are procedures carried out by divers in order to find a known or suspected target object or objects in a specified search area under water.There are a number of techniques in general use by Commercial, Scientific, Public service, Military, and Recreational divers. Some of these are suitable for Scuba, and some for surface supplied diving. The choice of search technique will depend on logistical factors, terrain, protocol and diver skills.As a general principle, a search method attempts to provide 100% coverage of the search area. this is greatly influenced by the width of the sweep. In conditions of zero visibility this is as far as the diver can feel with his hands while proceeding along the pattern. When visibility is better, it depends on the distance at which the target can be seen from the pattern. In all cases then, the pattern should be accurate and completely cover the search area without excessive redundancy or missed areas. Overlap is needed to compensate for inaccuracy.