The incident happened around 4 p.m. near 59th Street and the beach.
According to officials, the Sea Isle City Beach Patrol was alerted after a man suddenly went underwater.
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.
The man was taken to a hospital, where he was later pronounced dead.
Authorities have not released the man's identity.
Additional details about the circumstances surrounding the incident have not been released.