Fun with infinite tasers.
If the ship is being besieged by a malicious minisub, Security personnel can fight back by going to the Submarine Bay (Security) right of Research and Medbay and board any of the three security minisubs in this hangar, each outfitted with taser arrays that never have to worry about charge and special comms arrays that can open most station bays.
In case the subs need repairs, there's a welding supplies locker with welders and welding masks. In case the subs need extra/new parts, there's a ship component fabricator that can make them--given the right materials. There's also a mechanical toolbox that can suit both needs, and many more, laying rather unceremoniously on the floor. (What, NanoTrasen didn't even bother putting in a simple table for it?)
If the sub pilots expect to see some extra-vehicular activity, there's a side room with three racks holding jetpacks, O2 tanks, and security diving gear sets that protect against the heat of the Trench. This same side room also has pod phasers in case more lethal force is required and tractor beam modules that allowsubs to pull other subs, people, and other things towards itself.
Only subs (or, should they somehow appear, regular space pods) with Robustco Security Communication Arrays can raise and lower the hangar door for this sub bay, thus restricting access to only those vehicles.
There is no vent. Vents don't help catch crooks!
The APC this room is near the bottom left, on the outside of the southern wall of the side room.