The OPP say there was a dramatic increase in road, boating and snowmobile deaths in 2017.
Traffic data released Monday shows 343 people died on OPP-patrolled roads, making it a five-year high. There were 307 deaths in 2016.
Inattention was the leading cause, followed by speed, lack of seat-belt use, and alcohol and drugs.
Motorcycle deaths were the highest in ten years at 48.
Snowmobile fatalities reached an all-time record high with 29 deaths in 2017, and boating fatalities hit an eight-year high with 31 people dying.
The provincial police force says it's saddened and disappointed by the numbers, adding that tragic deaths will continue until all drivers respect and observe road, off-road, and marine laws that are designed to keep us all safe.