The incident happened around 4:30 p.m. near 59th Street and the beach.
Witnesses said members of the beach patrol were searching the water before locating an adult man.
Emergency responders were seen performing lifesaving measures on the beach before the man was taken to a hospital.
"They worked on him for a very long time," one witness said. "I mean, they even brought the chest compressions out."
The swimmer's condition was not immediately available.
Additional details about the circumstances surrounding the incident have not been released.