Livin' in yellow submarines.
Despite the name, this Submarine Bay (Mining) left of the Cargo Bay in the west/left/portside isn't just for Miners, and it's arguably not too useful for them. The Miners already have some pretty serviceable mining minisubs in the Tunnel Snake Mining Rig, so the four regular ol' yellow minisubmarines here are more of auxiliary subs. That's good news for the Engineers, the Mechanics, and especially the Quartermasters who have access here though, because that means they can use them to explore the ocean for treasures and profitable ventures.
That's not to say this place is completely useless for Miners though. There's a recharger here for recharging, among many other things, power picks, power hammers, and cargo transporters, an ore cart for storing and transporting minerals, and two big ore chutes on the left that can accept ore straight from crates (e.g. said ore cart) and can send it to Cargo and Mining. Also, someone apparently left a material analyzer on the floor.
Besides that, there's the usual floor wrench, ship component fabricator, and mechanical toolbox seen in all the other sub bays, though this time, you only have a tank of welding fuel and a locker of welders and welding masks for repairs. There's also a fire extinguisher and a tank of firefighting foam, presumably in case someone's sub gets so damaged it sets them on fire. One final thing of interest: a Duracorp construction module, essentially an limited RCD mountable for pods and subs.
There is no vent. Vents aren't yellow.
The APC this room is on the top wall, near the entrance into the main hallway.