Why must marine battery boxes and compartments be well-ventilated to the atmosphere on a sports vessel?

1. Lead-acid batteries emit flammable and explosive hydrogen gas (H2) during charging, which can accumulate in enclosed spaces and ignite from a small spark
2. Batteries require continuous oxygen flow to keep the engine exhaust clean
3. Ventilation allows seawater to enter and cool the battery plates
4. To prevent the battery electrolyte from turning into gasoline