Four other people were also injured.
At least one person is dead and another is missing following a deadly two boat collision in Muskoka this week.
According to Bracebridge OPP, officers responded to the crash at 7:40 p.m. on Wednesday after receiving reports of several distressed people in the water on Lake Rosseau near Windermere Marina.
A total of six occupants are believed to have been involved in the incident, four of which were pulled from the water by the OPP's Marine Unit with serious injuries.
One of the victims was pronounced dead at the scene and another is still unaccounted for.
An investigation has been launched and search efforts resumed on Thursday morning for the missing individual.