The body of Landon Walter Campbell, 61, Roan Mountain, was recovered in the main channel between Fish Springs Marina and the Butler Bridge.
Sheriff Chris Mathes said an autopsy had been ordered.
The Carter County Sheriff's Office and the Carter County Rescue Squad assisted the Tennessee Wildlife Resources Agency in searching for Campbell.
According to a TWRA news release, Campbell's body was found around 5:10 p.m. Sunday by an underwater remote operated vehicle.
The TWRA said Campbell apparently had collided with an island on the lake just upstream from Fish Springs. Officials were tipped off that an unoccupied bass boat was found at 10 a.m. and that another witness had seen the same unoccupied boat, with navigational lights being displayed, on Saturday evening at 10 p.m.
TWRA learned the man had launched his boat at the Rat Branch boat ramp several miles from the site of the accident. They found the man’s empty trailer and truck there and notified his family. The family told them the man suffered several medical conditions.
The accident remained under investigation.