On October 13, 2001, a 28-year-old male volunteer fire fighter (the victim) drowned during a multi-agency dive-rescue exercise. The dive exercise included a dive coordinator, an assistant dive coordinator, and seven divers. The site of the incident was a man-made lake that is owned and maintained by a private club. The dive coordinator and assistant dive coordinator had sunk a boat and two mannequins in the lake to simulate a boating incident. Four of the divers, including the victim, were on their second dive when the victim failed to surface. Dispatch was notified of the missing diver, and additional search-and-rescue crews responded to the scene with two rescue boats. The victim was found in the area of his last known location, approximately 1 hour and 15 minutes after he was last seen by his dive partner. He was transported to a local hospital where he was pronounced dead. NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments should: develop, implement, and enforce standard operating procedures (SOPs) regarding diver training; ensure that each diver maintains continuous visual, verbal, or physical contact with his or her dive partner; ensure that a backup diver and a ninety-percent-ready diver are in position to render assistance; ensure that the dive coordinator stays informed about the rates of air consumption by divers; provide divers with refresher training on the hazards of lung overexpansion injuries and prevention measures.