New Hampshire state police said Richard Degregory, 51, of Tyngsboro, hit the tree while going 20 mph on the lake in Laconia.
Police say four people have been injured in boating on Lake Winnipesaukee.
Two people are facing charges over a boating crash in Ipswich this past summer.
Police said one of the vessels was “unmanned and out of control” when it hit the other boat in the Ipswich River.
Authorities say a 10-year-old boy who was fishing with his father in a western Massachusetts lake was killed when their kayak was struck by a speedboat.