Why did the Titanic sink despite having watertight bulkheads?

The Titanic was designed to meet a two-compartment standard, meaning the ship could remain afloat if any two of its compartments were flooded. However, the collision with an iceberg on April 14, 1912, caused damage that breached at least five compartments.1

From the perspective of naval architecture, it is impractical to build a passenger ship capable of surviving all possible flooding scenarios, as the necessary subdivision would severely limit the use of interior space. While the bulkheads could not prevent the ship from sinking, they successfully slowed the flooding, allowing the vessel to remain afloat for two hours and forty minutes.1

Additionally, investigations of the wreckage have revealed that the impact did not create a single long gash, but rather caused brittle fracturing and the separation of seams in the hull plates. Some experts have also suggested that the quality of the steel or the strength of the rivets may have been contributing factors to the extent of the structural failure.2