||An underwater sensor for detecting dissolved methane concentration. The instrument operates according to the Law of Henry, whereby partial pressure gradients between the detector and surrounding water causes gas molecules to diffuse through the detector room's protective silicone membrane. The dissolved methane concentration in the outside water is directly correlated to that in the detector room, and can thus be calculated through a calibration formula. Concentration ranges vary with model version, and if the optional ranges are also included, they span: 10 nanomol/l - 100 micromol/l in the Classic METS (for long-term monitoring or low-speed profiling), 10 micromol/l - 2 millimol/l in IR-METS (for high concentrations and anoxic environments), 2 - 150 millimol/l in W-METS (for work at over-saturation), 100 nanomol/l - 150 millimol/l in K-METS (for mobile deployment, e.g. profiling, ROVs, AUVs). Standard temperature range is 2 - 20 degC; optional is 10 - 30 degC, but can be extended if required.