Submarine Ballast & Buoyancy (2D)

A submarine's hull volume never changes, so the only lever it has over its own buoyancy is its average density — controlled by flooding or blowing the main ballast tanks. This 2D side-view cross-section shows exactly that: drag the ballast slider toward 100% and the hull floods, its average density climbs past seawater's 1025 kg/m³, and Archimedes' principle — F_b = ρ_sea·V_hull·g against a weight of mg — sends it sinking; blow the tanks toward 0% and the lighter hull rises. A small trim tank lets you fine-tune toward the knife-edge of neutral buoyancy, where the hull holds depth on its own, exactly as the site's interactive 3D submarine model demonstrates. A live gauge tracks depth against water pressure, since real submarines gain roughly one extra atmosphere of pressure every 10 metres they descend.