Abstract: The present invention relates to a method and to a device for in situ underwater detection of physicochemical parameters in a body of water with a particular focus on using the acquired data for prospecting for potential reservoirs rich in hydrocarbons. The present invention provides a method for in situ real-time underwater detection of physicochemical and optionally biological parameters in a body of water by using an instrumented detection carrier. The present invention secondly provides an underwater instrumented detection carrier for in situ real-time detection of physicochemical parameters in a body of water comprising an autonomous underwater vehicle (AUV) arranged to use an instrumented module (or “payload”), capable of completing programmed missions without human intervention and configured to carry out the method provided by the invention.