The body of 66-year-old Robert Hammond of Hanson, Massachusetts was found around 12:45 p.m. on Saturday, according to the Maine Association for Search and Rescue.
Officials found Hammond's boat on Thursday afternoon near the southern end of Moose Island.
Wardens say after piecing together a timeline, they were able to determine that Hammond was traveling south into Greenville and docking at the public landing.
Officials say he then purchased some gas from a local store was heading back north on Moosehead Lake when for some reason he made a 180-degree slow turn, stopping on the shore of Moose Island when wardens would eventually find his body.
The warden service reminds boaters to wear a life jacket when on a watercraft.