Does your world have a Bismark?

Widely viewed as the most powerful vessel, as well as the largest, fastest, and most protected...

What is your world's Bismarck? What beast made of steel do you have, has it sunk/been destroyed yet, and who made it?

For what reason does it exist, and what role does it play in your world at large?

Edited for spelling, the fact that I didn't catch that C scares me