The Titanic was in fact called "the unsinkable ship".
The Titanic was the biggest and most luxurious passenger ship, whose construction finished in 1909. It was designed to include the latest technologies in terms of safety. Its double-platted bottom was divided in compartments, and each compartment had doors that would close if water had entered inside, so that the flooding could be isolated in a single section and the ship could remain afloat.