Drowning is potentially fatal. Physiologic responses to aspiration of water differ according to whether the water is salt or fresh; whether these responses are significant depends on the volume of fluid aspirated. Resuscitation efforts should be started at the scene of the accident. Oxygen therapy is essential. Many patients require continuous positive airway pressure or positive end-expiratory pressure to reverse hypoxemia. Physiologic responses induced by ice-water submersion can be protective during the initial insult. The prognosis for submersion injuries is guarded and is influenced by several variables.