Short S.25 Sandringham

The seaplane left Buenos Aires harbor at 1152LT bound for Asunción with intermediate stops at Rosario, Corrientes and Formosa. Few minutes after takeoff, the captain encountered oscillations and difficulties to control the airplane so he decided to return to Buenos Aires for a safe landing. Unfortunately, it was not possible to land immediately because of the presence of ship in the channel. Following several circuits, the pilot-in-command attempted to land when the airplane crashed into the sea few hundred yards off shore. A crew member and eight passengers were killed while 41 other occupants were injured. The aircraft was destroyed.

Crashed in unknown circumstances into the Ubangi River off Bangui.

While taxiing in the harbor of Port Vila, ready for takeoff, the pilot in command was apparently forced to make an evasive maneuver due to the presence of canoe's crossing his path. Doing so, the seaplane hit coral that punctured the bottom of the fuselage, causing water to penetrate into the aircraft that sank on its nose and was partially submerged. All occupants evacuated safely while the aircraft was written off.
Photos via http://www.aussieairliners.org/

Shortly after takeoff from the bay of Vagsfjorden off Harstad, while in initial climb, the seaplane stalled and crashed into the sea. All 33 occupants were quickly rescued and the airplane sank an hour later.

The crew was completing a flight from Oslo to Tromsø with an intermediate stop in Trondheim. On approach to the bay of Stjørdal, about 25 km east of Trondheim, the pilot in command encountered marginal weather conditions with strong cross winds. Upon landing on rough sea, the seaplane bounced and hit violently the water surface. The fuselage broke in two, causing the front section including the cockpit to separate from the rest of the aircraft. Sixteen passengers and three crew members were killed.

While cruising at an altitude of 13,000 feet in poor weather conditions, the four engine seaplane hit the slope of a mountain located 31 km northeast of Harstad. The wreckage was found in a rocky are some 290 meters from the summit and all 35 occupants were killed. It is believed that the aircraft was slightly off course at the time of the accident.
Crew:
John Buer, pilot,
Karl Bengtsen, copilot,
Johannes Daae Risnes, navigator,
Paul Idland, radio operator,
Gunnar Michaelsen, mechanic,
Atle Fedje, steward,
Ester Mildrid Løsnes, stewardess.

The approach to Bahrain was completed by night and the crew landed in the Marine Base at an indicated speed of 85 to 90 knots. Upon landing, the seaplane had a tendency to nose down so the captain counteracted with the control column and increased power simultaneously. The aircraft bounced, left water for about one to two seconds and then veered sharply to the left. Out of control, it plunged into water and came to rest. Three crew members and seven passengers were killed.