English: Schematic of use of active and passive sonar to detect bubble leakage from seabed (seeps, carbon capture and storage facilities) and gas pipelines (originally from Leighton, T.G. and White, P.R. (2012) Quantification of undersea gas leaks from carbon capture and storage facilities, from pipelines and from methane seeps, by their acoustic emissions, Proceedings of the Royal Society A, 468, 485-510 (doi: 10.1098/rspa.2011.0221)).