The dolphin was found at about 11 a.m. this morning, near the area it was originally spotted, at Cropsey Avenue and Bay 54 Street.
The Riverhead Foundation will determine if the dolphin is the same one as yesterday. They will also before a necropsy to determine the cause of death.
NYPD officials attempted to help the dolphin swim away on Thursdaym hoping it would be freed by the late afternoon high tide.
The rescue operation began Thursday morning near Bay 54th street and Cropsey avenue in Coney Island.
A bystander reported seeing the dolphin in distress just after 11:00 a.m. Officials say the dolphin swam into Coney Island Creek about 3/4 mile during high tide.
The NYPD's emergency services unit and harbor patrol tried to help direct the dolphin out of the creek
Shortly after 3:00 p.m., the dolphin attempted to beach itself, and then suddenly disappeared under the water.