An off-duty county lifeguard rescued a kayaker in his 60s Thursday afternoon at Honolii Beach Park in Hilo, Hawaii County Fire Department said in a news release.
Surfers pulled the man to shore.
When firefighters arrived at 5:10 p.m., they found a county lifeguard performing cardiopulmonary resuscitation on the man, who was slumped over his kayak before being knocked into the water, the Fire Department said.
The surf was 2 to 4 feet high, and the river was at a moderate level.
The man was treated and taken to the Hilo Medical Center in critical condition.
It is unknown what caused him to go unconscious, the Fire Department said.