On 30 April 2012, at around 19:50 MST Dale Oen was found unconscious in his hotel bathroom after having suffered a heart attack, caused by chronic, undetected coronary heart disease, a rare disease for a person of his age and fitness. He was found in his bathroom by one of his teammates, and CPR was performed before Dale Oen was brought to Flagstaff Medical Center. He was pronounced dead at 21:00 MST. Dale Oen was attending a training camp with the Norwegian swimming team in Flagstaff, Arizona at the time of his death.