Yes, the aircraft could be dived into the sea from cruise in less than two minutes, or if it was vaporized, it would never have come down.
The detailed seabed debris fields from Swiss 111 or AF447 for point impacts on the ocean surface, or from Lockerbie and TWA for the places where high-altitude disintegration put things at sea level mean that there isn't going to much problem reconstructing which took place once the wreckage is found.