Oops...

 What happens when a submarine runs into an underwater mountain? 

They wonder how it suddenly appeared, I'd guess...

Maybe windows would help? 

At least they managed to get somewhere (in this case, Guam) without sinking.

Welcome to the world of the USS Francisco, which ran aground in 2005 after hitting an underground seamount. It managed to limp into port without sinking. Although the mountain was not on the maps the boat's commanders were using at the time, they were warned about an "obstruction" in that area.

Well, they know about it now. 

The USS Connecticut did the same thing in 2005 in the South China Sea. The sub's commander, XO and chief of the boat were all relieved of duty. To be fair to them, it should be pointed out that only an estimated 50% of the ocean bottom has been mapped. On the other hand, the South China Sea is fairly extensively traveled. (More about the San Francisco, as well as the USS Georgia, which ran into a buoy, via this link, as well.)

Other weird accidents here, thanks to Bored Panda.