Many people think the worst thing that can happen is to be locked inside a strange building with the key hidden somewhere and your life in danger. However, being inside a submarine that is partially submerged in the water and will soon drive towards the bottom of the sea can be worse, since calling out for help won't help and there will be no window, while there is not much oxygen to be used. This is exactly the situation that you found yourself into and running against the clock to find hints that will open up the tunnels is your only way out. Even taking too long you can reach the exit, but then you won't be able to swim to the surface and will die drowned. Think fast and find keys and papers left by the criminal who did this to you and plan your vengeance later, safe at home.