Submarine Sabotage

You are currently serving aboard the USS Ibis, the first of the US Navy's top-secret Puny class submarines. You were doing some routine maintenance at the aft end of the submarine when the sirens sounded. You thought this might have been a training exercise until you noticed a whitish-colored gas approaching you from the aft bulkhead. Training and instinct took over. You couldn't get to a gas mask in time, so you dived into the nearby airlock and closed the air-tight hatch behind you. You are now alone and have no idea what is happening throughout the rest of the sub. You can't leave the airlock through the inner hatch (the one you entered by), or you'll get gassed, and you can't leave through the outer hatch, or you'll drown. What can you do?

This is a traditional text adventure that was written for PunyJam #3.