Moonpool

Vertical opening through the hull of an offshore vessel — typically 6–8 m square or round — through which equipment, divers, ROVs, or subsea hardware are deployed in a sheltered indoor location. The moonpool eliminates the wave and wind exposure of over-the-side launch, allows much larger payloads, and on drillships houses the riser. Hydrodynamic design has to manage the moonpool's free-surface resonance, which can produce vertical water motions of several metres at the resonant heave period and disrupt diving operations.