 The NTSB report says that the operator, Alaska Float Ratings, stated the flight's purpose was to provide dual-flight training as part of a single-engine sea add-on rating. Alaska Float Ratings also revealed that the planned destination was not Crescent Lake but Bench Lake, which is about 10 miles northeast of Crescent Lake. The flight plan was for Bench Lake. We don't know if they went there and then went over to Crescent Lake. Those details will become available as the investigation continues.