Fresh Air
First, we should acknowledge that the cartoon’s facial expression is a lot calmer about an open submarine window than we would expect most of our faces to be. Drowning hundreds of meters below sea level would undoubtedly generate a terrifying image.
However, the statement that “there will be no fresh air outside” is incorrect. Whether you’re on a boat, an airplane, a submarine, or even a train (wink), fresh air is always available. You won’t be able to breathe it in, but it’s there for you.