[High Voltage]

pffff, that's nothing; A great number of books deal with a Capitanleutnant Bernard who was not even aware that his submarine had the ability to submerge.
He survived the war by patrolling what he thought was the English Channel but later turned out to in fact be the Amazon river in Brazil.

if you want a real challenge try and do what I consider to be a fairly challenging mission: 1944 - Gibraltar - type II U-boat - Surfaced - Flak gun only!

Then we'll talk.