Back in my days at Time Computers I took a call from a Navy Lieutenant whose laptop had failed and (he said) required urgent replacement as he needed it to plot his navigation courses.
The call sounded like he was down a gurgling drainpipe, and he explained the sound quality by saying he was "underwater" - but couldn't say where or which boat (but hinted it was a big submarine the Russkies would be keen to find.....). Presumbly some kind of secure satellite link tied into the phone system.
Bit of a catch-22........if the boat and its location were secret, and it was underwater, how the heck were we supposed to do an exchange on the laptop? I think in the end we couriered a replacement to Faslane and let the Navy work it out from there