The main tasks of acoustic sounding of gas manifestations are the search, localization (mapping) of gas seeps, and assessment of methane flows from gas-emitting areas of the seabed into the water column. This chapter presents the hardware and methodological support for the field hydroacoustic observationshydroacoustic observations carried out on various research vessels (“Kiev,” “Professor Vodyanitskiy,” “Vladimir Parshin,” and others). The focus is on the acoustic characteristics of single gas bubbles and their clusters in gas seeps. This is necessary both for the development of methods for acoustic diagnostics of gas emissionsDegassingcold degassinggas emissions (including the selection of optimal measurement modes and interpretation of sounding results) and for ensuring the efficiency of hydroacoustic systems for detection, navigation, and protection of water areas under reverberation interference from gas seeps. The localization of gas-emitting sources was determined using data from a GPS receiver located coaxially with the antenna of the hydroacoustic system performing the search. To estimate methane fluxes, direct measurements of backscattering cross-sections (with subsequent inversion into bubble sizes) and ascent velocities of single gas bubbles observed outside gas seeps were carried out using the capabilities of a split-beam antenna and trajectory measurement techniques. The “visible” (acoustic) height of the flares and their shape depend significantly on the vessel’s motion parameters, the current velocity profile, and hardware and software settings. When crossing a flare along the general direction of the current, it is registered in the maximum depth range, and its “visible” height is close to the actual height for hydroacoustic systemshydroacoustic surveyhydroacoustic systemswith a wide recording range. The probability of detecting a flare is maximum when crossing it in a perpendicular direction.