Snorkelers pulled an unconscious 19-year-old California woman from the ocean at Honolua Bay in West Maui.
The woman was snorkeling at the popular spot with family members when other snorkelers found her floating unresponsive.
They pulled her to shore where bystanders performed CPR.
Emergency personnel responded to a 12:21 p.m. call Thursday for an unresponsive woman.
Firefighters arrived at 12:29 p.m. at the bay and took over CPR until paramedics arrived to give advanced life-saving measures, the Fire Department said in a news release.
The woman eventually regained a pulse, and paramedics rushed her to the Napili Ball Park, where a waiting helicopter medevac stood by.
She was flown in critical condition to Maui Memorial Medical Center.