SOLUTION: Robust and self-supplied system for point detection and monitoring of underwater gas leaks from pressurized equipment or seabed hotspots. No cabling or power supply is required. A mechanical counter indicates the overall volume of gas collected and released. Automatic alarming via satellite beacons released to the surface. ROV friendly retrofit installation. BENEFIT: Continuous monitoring 24/7 of the plugged well | No need for frequent ROV inspections | Standalone unit, no power or network required | Cheap, flexible and easily installed