Lifeguards rescued a 34-year-old visitor this evening from nearshore waters off the Diamond Head lighthouse.
The man was taken by ambulance in critical condition to a hospital.
Ocean Safety received a 911 call at 6:18 p.m.
Lifeguards responded by rescue watercraft and were able to find the man immediately upon arrival, brought him to shore and began cardiopulmonary resuscitation.
They transferred care to Emergency Medical Services personnel, who continued to provide advanced life support and transported him to a hospital.
Emergency Services Department spokeswoman Shayne Enright said that it is unknown how the man got into trouble, but it does not appear he was surfing.