What happened
A pilot was departing a remote lake in a float-equipped Cessna 180A, N94259, after dropping off two hunters. The area was experiencing windy conditions caused by a nearby glacier, resulting in waves approximately 3 to 4 feet high and estimated winds of 30 knots.
During the takeoff roll, waves washing over the top of the floats caused several hard impacts against the aircraft's floats. In response, the pilot aborted the takeoff and taxied across the lake in search of calmer water. During this taxi, the left float began to take on water, causing the airplane to roll over. While the aircraft did not sink immediately, the pilot exited the cockpit and climbed onto the inverted floats.
A rescue attempt was subsequently made by the pilot of a Bell 206B, N84TA. While the helicopter was hovering near the overturned Cessna, it entered a dynamic rollover and crashed. The pilot of the Cessna sustained serious injuries. Following the rescue attempt, the Cessna 180 sank into the lake.