How do watertight doors work?

Watertight doors are designed to prevent the passage of water between different compartments of a vessel, particularly in the event of flooding. They typically feature a robust frame and a sealing mechanism, such as rubber gaskets or seals, that compresses when the door is closed to create a watertight barrier. The doors can be manually operated or equipped with hydraulic or pneumatic systems for quick closure during emergencies. Additionally, they often include safety features like locking mechanisms to ensure they remain securely closed under pressure.