It is a mistake for the police or a medical examiner to assume that drowning was the cause of death for a body recovered from water. The diagnosis of drowning requires a full investigation by the police and the forensic pathologist. It should include a detailed account of the circumstances surrounding the death, information on the victim's activities prior to entering the water, information on the deceased's social and medical history, and a full autopsy that includes microscopic examination and toxicology. Determining whether the person was alive upon entry into the water is critical. If the investigation supports a diagnosis of drowning, two additional questions must be addressed: why the victim was in a situation that put him/her at risk for drowning and why the victim was unable to survive in the water or get out of the water. The chapter provides suggestions for answering these questions. Various conditions and circumstances that should be explored are shallow-water blackout, the relationship of natural disease to the drowning event, drugs and alcohol associated with drowning, the involvement of dangerous marine life in the death, nonaccidental drowning, and postmortem changes in water. Also discussed are autopsy findings associated with drowning, drowning tests, pathophysiology associated with fresh and saltwater drowning, injury and death in cold water, expected human responses to immersion in cold water, and injury and death associated with scuba diving. Extensive photographic exhibits and 68 references