I used to live on a Submarine, SSBN 599N. Fire was more feared than flooding. While my boat was a nuclear boat the power backup was diesel. Hydraulics everywhere, electricity everywhere and plenty of stored diesel fuel. All you need is a match or a spark in the wrong place.
Fires happen and we would train for them over and over again. The luxury we had was that we had EAB (Emergency air breathing) masks with air manifolds every several feet. One of the things you had to learn was to find the manifolds in the dark or blindfolded. If you couldn’t do that you could become a casualty during a fire. PKP (Purple K Powder) was your friend, water is a very dangerous thing to extinguish a fire with on a submarine. With loss of the reactor and below periscope depth you depend on the battery just like the old boats. One thing the battery didn’t like was sea water. Seawater in the battery would quickly supply the ship with some very toxic gases, worse than the smoke. The Battery is always at the lowest point of the boat, water seeks the lowest point. Under water there is no place for the smoke to go, no place for toxic gases to go and no place to get fresh air, very serious business a fire.
Interesting place a submarine.
Boy, no kidding. Being sealed in down deep kind of concentrates the mind, I suspect.