The bilge is the lowest internal compartment of a ship or boat's hull where water, oil, and debris collect. It acts as a sump (sump area) below the floorboards to protect the cabin from dampness and ensure vessel stability. Bilge pumps remove this collected "bilge water," which often requires careful environmental disposal.

Key Aspects of the Bilge:
Location: The lowest point in the interior hull, between the cabin floorboards and the bottom/keel.

Function: Serves as a catchment area for bilge water—a mixture of condensation, rainwater, and minor engine leaks.

Safety: Requires regular inspection and pumping to ensure the vessel remains buoyant and stable.

Structure: It is where the vertical hull sides curve to meet the flat bottom, often functioning as a structural junction.