I've been embroiled in a quite exciting mass-multiplayer PBEM game that is being reported upon both here in the EAW AAR Forum and in the Paradox Off-Topic Forum as Germany in the Central Powers.
In our last turn, I managed to run the entire German High Seas Fleet through the Strait of Gibraltar and into the Med Blockade Box, destroying every heavy ship that the French Navy had available.
Realistically, this should not happen or even be remotely possible.
To prevent this from happening, there should be some game mechanics included to make such a move more difficult to pull off.
One suggestion was to include mines in the Strait that belong to the British. That's an idea I happen to like, as it means that even if I had managed to sail the High Seas Fleet through the area, that the damage suffered may have prevented me from winning the battle against the French.
The only problem I see with this is that if Gibraltar somehow manages to be captured by the Central Powers, the CP will have no opportunity to effect the same conditions upon the Entente.
Another possibility would be to allow the artillery stationed at Gibraltar to fire upon enemy vessels that cross the region. The problem with this is that the way combat mechanics work, it would be hard to simulate the fact that most of the large capital ships would be forced to pass through the Strait in neat, easy-to-shoot lines. Perhaps some form of frontage mechanic could be utilized to make this more realistic, but I'm not sure.
One last possibility would involve modifying the map, making the Strait itself impassable except through Gibraltar itself so that you would need to control the region before being able to pass into the Med or out. This has the drawback that Submarines will be unable to sneak in or out (though from what I've read, the current was too strong for submerged subs to exit the Med).
What does the rest of the community think?