It happened along a stretch of beach that is not monitored by lifeguards and swimming is prohibited.
Two men went into the water and an eyewitness said one of them began screaming for help after his companion went under.
A passerby jumped in to rescue him.
"We kept doing CPR and then we had someone call 911 and we just kept doing CPR until they arrived," the witness said.
First responders then responded and took the man to the hospital.
His condition is unknown.