Most boating fatalities are the result of capsizing or falling overboard.
Most fatalities occur in small, open boats during good weather, mid afternoon on summer weekends. Most non-fatal boating accidents are the result of a collision with another boat or something in the water, rocks, pilings, debris. Most boating accidents are sudden and unexpected. There's little if any time to reach for a life vest, which is why you should wear one all the time. Many good swimmers have drowned because the alcohol they consumed distorted their ability to orient themselves, swimming down, instead of to the surface.