A day or so ago, someone posted that the sea beneath the flight path was some 50 metres in depth. That reminded me of something my late father told me when he was stationed at RAF KL in 1950's.
Once a week he would fly a STOL a/c from KL to the Shell oil company site in Borneo. He said the sea was so clear he could see shoals of sharks swimming beneath him.
It is surprising that if there are large sections of the aircraft in the area being searched, none have been found.