On ships, 'waterline' indicates how heavily a vessel is loaded. The cargo was heavy, bringing the ship closer to the waterline.
Pro Tip 2/3
Safety Marker
Below the waterline is critical for ships as breaching it can threaten buoyancy. During the inspection, they ensured no holes were below the waterline.
Pro Tip 3/3
Structural Boundary
The waterline separates the underwater hull from the above-water superstructure. The waterline is clearly visible, differentiating the red hull from the white deck.