A system and method for detecting and measuring phenomena relating to altimetric variations in the seafloor. The system including an autonomous submarine vehicle equipped with at least one interferometric sonar sensor configured to send an acoustic signal towards the seafloor and acquire the image of the seafloor generated by the reflection of said acoustic signal sent. The system also including a plurality of elements reflecting sound waves firmly fixed to the seafloor so as to outline a reference path for the passage of the autonomous submarine vehicle.