Breaking news: Submarines can also fly in the sky
Besides being a meme, factually, there are more planes than submarines in the ocean as in case of an emergency during flight, the plane can safely crash into the sea to reduce the chances of explosion. A submarine will always remain beneath the sea and will never be found in the sky (unless technological advancement decides to give it a try).
It took a long time for the joke and its understanding to arrive at this person as they assumed the post required submarines to acquire gravity-defying dynamics to ascend to the sky. Nevertheless, we sincerely hope the effects of memes are jokes to the person throughout the remaining days of their life.