Unusual light hovering over the Lake with no corresponding aircraft seen

In the Summer of 1978 I was returning to my hotel in Oakville, Ontario, with a friend when we both saw an unusual light hovering over Lake Ontario. There were no planes or helicopters associated with this light. It hovered approximately 100 - 200 yards over the surface of the lake. We watched it for over an hour before we went inside the hotel and told the desk clerk. He came out and watched it for quite a while before calling the police department. We didn't know who to call or what to think. The police told him to call the Canadian Coast Guard for the area and gave him the number. The Guard sent out a search plane, which we saw approach the light. The light didn't immediately leave, but it slowly lifted at an angle and gradually pulled out of sight. It was over the lake for over 5 hours because I think it was almost dawn when it disappeared. We heard nothing more about it.