Abstract: Gas monitoring apparatus associated with a remotely operated seabed system, the apparatus including a detector which is adapted so as to enable detection and/or measurement in real time the interception of shallow gas in a bore hole. In one form the gas monitoring apparatus is suitable for use with a drilling rig for drilling into a sea bed, the drilling rig including a drill string. The gas monitoring apparatus includes a housing with a collecting chamber therein for receiving drilling fluid returns which result from a drilling operation. The apparatus further includes a discharge conduit for discharging the drilling fluid returns from the collecting chamber, the collecting chamber and discharge conduit being configured so that the drilling fluid is discharged in a stratified flow which includes a predominantly dissolved gas containing phase, and if present a free gaseous phase.