A 35-year-old man suffered serious head injuries after his snowmobile struck a boat in King Township, police say.

The crash occurred shortly after 4 a.m. on Sunday in the area Keele Street and Lipchey Road, just north of Highway 9.

Police said the rider was thrown from the snowmobile after hitting a boat in his backyard. The man was not wearing a helmet.

The cause of the accident is still unclear. The York police’s major collisions bureau is investigating.

No one else was injured during the incident.