The owners of the huge vessel, White Star Line, had said the ship was " designed to be unsinkable" but people interpreted this as proof that it was completely invincible.
At the time, however, she was not only the largest ship that had ever been built, but was regarded as unsinkable, for she had sixteen watertight compartments.
That's why the crew intentionally ran the USS Nevada aground to save the ship but its survival is only part of the reason why this was known as the unsinkable battleship.