Originally Posted by
On_The_Top_Bunk
And if you think cell phones would have any useful info after being submerged in a saline solution at great depth for such a period you may have to go back to school for some more chemistry and physics classes.
SD cards and similar solid state storage are close on impossible to erase/destroy apart from being burnt. Data has even been recovered from SD cards that have had nails driven through them.
The electronics of the phone will die almost immediately on immersion but the solid state phone memory not at all. (A warning for all those who discard bricked cellphones one of the first things techies do on receiving such a phone is check and read the solid state memory and old SD cards, and run undelete to see if there is anything 'interesting')