U-boat

easy when enemy anti-submarine ships hardly detect the submarine and it is more difficult to hit
There is aviation (enemy, but very rarely)

The middle distance is more difficult but not more dangerous than the difficult one
aviation (there is, but a little rare)

difficult this is when the detection range is increased and enemy anti-submarine ships are hit almost without problems
aviation (often available)

/submarine

air:100%
(will decrease if underwater)

discipline:100%
(usually discipline is needed to maintain readiness in case there is not enough, the crew will panic or refuse to carry out the task)

energy:100%
(there is a diesel engine, so it is possible to replenish energy, but not in underwater mode)

lamp color: red/blue/normal
(red is usually needed to see better in case of a fight/blue to warn not to disturb the silence so that the boat is not found/stable normal color like nothing happened or is happening)
pump:on/off

(needed to pump out water only on the surface)
5 compartments in general

1 bow torpedo compartment:?%
2 bow battery compartment:?%
3 central post:?%
4 feed battery compartment:?%
5 diesel/electric motor compartment:?%

no holes: 0%
There are holes: it depends on the size; the larger the hole, the faster the compartment will fill up.

enemy trade convoys only if a neutral convoy sails to an enemy port it must be inspected for support against us
and get away from anti-submarine ships so as not to be noticed

people may be in the submarine for support (german people in the second world)
{{name of German}} "talk like that"
{{name of German}} has its role in the submarine