The pilot of the float-equipped DHC-3 Otter, C-GUTL, was departing from the Sportsmen Airways base near Fort Frances, ON. During the take-off run, the aircraft was headed southwest, into a wind which was estimated at 30 knots plus gusts. Shortly after lift-off, the aircraft passed a point of land and the wind gusts increased in strength and changed direction. The pilot reported that the heading of the aircraft suddenly changed from south-westerly to north-westerly. The pilot became doubtful that the aircraft could clear the shore and the trees which were now in the aircraft’s path and elected to reduce engine power and land. As the aircraft was touching down, the gusty wind lifted the tail and flipped the aircraft on its back, in about seven feet of water. The pilot and seven passengers were not injured. They exited the aircraft and were taken to shore in a boat. The aircraft sustained substantial damage and drifted back to shore.