This is the bottom-most internal space of a vessel, located below the floorboards or engine room deck plates. Gravity causes any leaked water, condensation, fuel, or oil to drain into this area. Ships rely on dedicated pumps to empty this space regularly, as accumulated liquid can destabilize the vessel through the free surface effect or cause internal corrosion.
Heard on the job
The high-level alarm is sounding, send the wiper down to check if the bilge pump lost suction.