Man the torpedoes! There's a [THREAT] and need to launch a [TORPEDO TYPE] torpedo at it to keep it away! Except that Random Events requiring the use of Torpedoes like that haven't been implemented yet, so these Torpedo Bays in the northern/fore/bow of the ship above the Bridge are more for launching dead people out of them as a burial at sea than dealing with threats. In fact, said threats often take the torpedoes here and use them on the crew, rather than the other way around.
There're two Torpedo Bays, Starboard Torpedo Bay (that's right/west for you land-lubbers) and Port Torpedo Bay (conversely, left/east), and aside from being mirror images of each other, are pretty much exactly alike. Each one is accessible only to Heads of Staff and other people with Bridge access, and each one has, of all things, a mechanical toolbox and a high-capacity canister of air mix, alongside torpedo machinery.
Speaking of torpedo machinery, read the in-game Torpedoes and You guide for a brief description of the torpedo types and how to launch them. Check out the Torpedoes page for an more in-depth guide that also discusses other uses for torpedoes and the torpedo tubes.
There are no vents. While torpedoes do need compressed air (check out that bubble trail as they go), they get theirs from this specialized system that uses a kind of vent different from the one that refills air in rooms.
The APC for the Starboard Torpedo Bay is on its right wall, over table, while the APC for the Port Torpedo Bay is on the left wall, also over the table.