What happened
The pilot was operating a floatplane on a positioning flight intended to meet with fishermen and subsequently transport them to an alternative location. The flight involved navigating waterways to reach the pickup point.
Upon arriving at the river, the pilot executed a landing. Following the touchdown, he initiated a step taxi maneuver to enter a side channel designated for the loading and unloading of passengers. During this low-speed phase of operation, as the floatplane was coming off the step, the aircraft struck a submerged sandbar. The obstruction was not visible from the cockpit.
The impact with the unseen sandbar caused the floatplane to nosed over. No further details regarding injuries or specific damage extent were provided in the source material.