A 54-year-old swimmer who became distressed while participating in Monday’s Waikiki Roughwater Swim has died.

He has been identified as Gustavo R. Penilla of California, according to the Honolulu Medical Examiner’s Office. The cause of death was drowning and the manner of death was classified as an accident.

Lifeguards along with the Outrigger Canoe Club and a private water safety company responded to a swimmer in distress in waters off Waikiki shortly after 9:30 a.m. Monday and administered cardiopulmonary resuscitation, according to the Honolulu Emergency Medical Services Department.

Once on shore, lifeguards continued CPR until Emergency Medical Services personnel arrived and took over with advanced life support.

Penilla was taken to The Queen’s Medical Center in critical condition where he later died.

The annual Waikiki Roughwater event was held on Labor Day following a two-year hiatus due to the COVID-19 pandemic.

More than 700 swimmers participated in the 2.4-mile race which started at Sans Souci Beach and ended at Duke Kahanamoku Beach near the Hilton Hawaiian Village Resort.