The assault happened at 3:00 in the morning on the beach at Point Pleasant, after the woman left friends. She possibly met her attacker earlier that night.
Images of a person of interest were captured on a surveillance camera along the boardwalk at Point Pleasant Beach.
Authorities are hoping someone will make out the images enough to identify him.
The attack happened along a stretch of beach between the jetties and Martell's restaurant, where the woman had been out with friends earlier Sunday evening.
"Police got a call from an establishment that a patron was sexually assaulted at 3:00 a.m.," Ocean County Prosecutor Marlene Lynch said.
"People assume it's safe because it's the Jersey shore, and they see families, but it can happen anywhere," Malboro resident Melissa Brenman said.
"Surprised it happened here, but not surprised it happened with the world we live in," Jessica Rooney, a Point Pleasant resident, said.
The victim was treated at a hospital.
Police closed off that section of the beach for several hours Monday, successfully gathering some evidence.
Again, this man is being called a person of interest only by the prosecutor. He is in his mid to late 20s, 5'8 to 5' 10, 180 pounds. He was wearing a white shirt, khaki shorts, and has dark hair, dark eyes, a deep tan and a heavy foreign accent.
"We're not making accusations. We would just like to talk to him because we think he may have vital information on this incident," Lynch said.