Back in 1973 the RAF recovered a Halifax bomber from the bottom of a ffiord in Norway. I think it is now on display in the RAF museum.
The condition of the aircraft after 30 years submerged in fresh water was quite good apart from the damage sustained during the war. On recovery it was subjected to some preservation/restoration procedures.
I am not saying that the Spitfires - if found - are in the same state but perhaps they will not be as bad as some are thinking.
Just thinking out load.
Aaron.