A 16-year-old girl swam nearly a kilometre through cold, rough water, then walked two kilometres through the bush to get help after the boat she was in capsized on Lost Lake, near Sioux Lookout.

Provincial police have released new details of the June 19 accident that killed three people.

Sioux Lookout Staff Sergeant Nathan Schmidt said the survivors spent nearly five hours in 8 C water after their boat was swamped by water and rolled over, between Frenchman's Head and Hudson.

Two brothers, 19-year-old Simon and 30-year-old William Chisel were unable to keep their grip on the 16-foot aluminum boat in the rough waters.

"The remaining occupants eventually tried to lighten the boat by taking the motor off of it and dropping it into the water," Schmidt said.

"The waves were very high that day and it was very difficult swimming, trying to move a boat across the lake to get to shore."

Survivors brought boat to shore

Schmidt said a 16-year-old girl eventually donned a life jacket and began swimming the 800 metres to shore.

"We know where she landed on shore, because it's where she dropped the life jacket and basically walked two kilometres until she arrived in the community of Frenchman's Head," he said. The teen then asked someone to call police.

The other occupants of the boat — two women and three men —  had managed to get the boat to shore when police arrived, Schmidt added. They were loaded into police boats and taken up river to a bridge, where an ambulance took them to hospital in Sioux Lookout. 

One man, 39-year-old Kevin Brisket, was declared dead upon arrival. 

Schmidt said police have recovered the boat's motor and are investigating to see whether it was running at the time the boat capsized.