Daphne Yun, a spokeswoman for Gateway National Recreation Area and the National Parks Service, says the 12-year-old was with her family when she got into trouble in the ocean off Beach E just before 6 p.m. Sunday.
Lifeguards, who were still on duty, pulled her from the water and administered CPR.
The girl was rushed to Monmouth Medical, where she died Monday morning.
She has since been identified as Bianca Palma, from Elizabeth.