Just some info for ye.
the aircraft would probably been in ditching(landing on water) config meaning that it stayed a float a lot longer than if it had not been.
When the pushbutton switch 13HL is pushed (the ON legend comes on) and the aircraft goes into the ditching configuration. This closes:
.the outflow valve 10HL,
.the pack flow control valves of the flow control units 23HB (24HB),
.the avionics skin air inlet valve 15HQ, if open,
.the avionics skin air outlet valve 22HQ, if open,
.the emergency ram-air inlet, if open,
.the fwd cargo isolation valves 4HN (5HN), if installed.
This basically would have prevented the cabin from flooding through the air conditioning and avionic cooling system
also if APU had been running, assuming the APU generator was good, then all hyd systems would have been available to the crew via electric pumps to blue and yellow systems and green system via PTU