The prosecutor's office said it was around 8:44 p.m. when rescuers were called to Fischer's Pit in Berkeley Township for a swimmer in distress.
The pit, also known as Fischer's Lake, is a deep and inactive sand and gravel mining pit filled with water.
"The pit is difficult to access and is an extremely dangerous unprotected place to swim. The steep and sandy banks make it very difficult for an individual to find enough support to exit the water filled pit," Ocean County Prosecutor Joseph Coronato said in a statement.
"Individuals should never swim there," the statement continued.
Rescuers entered the pit and recovered the victim, 18-year-old Gary Douglas of South Toms River.
Douglas was pronounced dead at the hospital.
Coronato said an investigation into this incident continues.