On September 14, 2015, about 1330 Alaska daylight time, a float-equipped Dehavilland DHC-2 MK.1 airplane, N676SP, collided with a tree and a river bank during a water takeoff from the Nowitna River, approximately 58 miles to the north west of Nikolai, Alaska. The commercial pilot was not injured, and the airplane sustained substantial damage. The airplane was registered to Sportsman's Leasing LLC, Anchorage, Alaska, and operated by Sportsman's Air Service, Anchorage, under the provisions of 14 Code of Federal Regulations Part 91, as a day, visual flight rules, positioning flight. Visual meteorological conditions prevailed and a company visual flight rules flight plan was filed. The flight originated from the Yukon River at Galena, Alaska. According to the pilot, a flight of two company airplanes proceeded empty to the river for a passenger and cargo pick up. The accident airplane landed at the primary landing site on the river and instructed the waiting boats to move down river to the longer, alternate landing site where the second airplane was waiting. While departing the primary site, upon reaching the step phase of takeoff from the river, the left wing impacted a tree, and the airplane then impacted the river bank. The pilot reported that he was unable to achieve sufficient directional control to avoid impact with the tree and river bank. The airplane sustained substantial damage to both wings and the fuselage. WRECKAGE AND IMPACT INFORMATION The photographs of the wreckage supplied by the pilot, showed that the airplane came to rest on top of a dirt and rock embankment along the river, and the float support structure had collapsed. The right float had rolled on its right side, broken in half, and the forward section lay under the fuselage pointed to the left. The left float appeared to be intact. Both of the water rudders appeared to be in the up/stowed position. The right side of the fuselage, aft of the right float attachment point, displayed buckling of the metal skin. Both wings appeared to be bent aft as evidenced by deformation at the forward portion of their wing roots. The outboard leading edge of the left wing showed damage consistent with impacting an object. Due to the remote location of the accident, the National Transportation Safety Board investigator-in-charge did not examine the wreckage.