Two-year-old Diane Cecile Mary Prevost disappeared from Grundy Lake Provincial Park, Ontario, in September 1966 while her family was camping. Her father Bernard was fishing on a dock and her mother Claire and Diane’s siblings were near the shore looking for frogs. Diane, who was afraid of the water, had been playing in the sand and said she wanted to go back to the family campsite about 500 feet away; her father told her he would take her after untangling his fishing line. In a brief lapse of attention Diane vanished and an immediate family search turned up nothing.

Police, military personnel, search dogs and divers combed the park and lake for four weeks. Dogs followed her scent only a short distance before it stopped, a detail that led investigators to consider the possibility she was taken and put into a vehicle. The family urged police to close the park gates that day but that was not done. Over the decades relatives have pursued tips, used age‑progressed sketches and excluded some claimants by DNA, but Diane’s whereabouts remain unknown. Does anyone have information about Grundy Lake in 1966 or sightings that could help this case?