The victim, 39-year-old Brian Petronaci of Hopatcong, was found by police at about 2:30 a.m. Sunday.
Detectives say the snowmobile struck a rock in the area of Liffy Island, which is located across from the Lake Forest Yacht Club, causing the vehicle to crash into trees.
Petronaci was pronounced dead at the scene.
Jefferson Township police were asked at around 1:40 a.m. to assist Hopatcong police in trying to locate Petronaci after he went missing.
----------
* More New Jersey news
* Send us a news tip
* Download the abc7NY app for breaking news alerts