The invention notably relates to a method for controlling depth of a seismic cable having ballasts spaced apart along its length and providing a neutral buoyancy to the seismic cable, the seismic cable being adapted for midwater data acquisition, each end of the seismic cable being connected to a respective surface autonomous vessel exerting tension on the cable through a respective lead-in cable having a negative buoyancy, the method comprising, with respect to a target depth, varying the deployed length of each lead-in cable and/or the tension exerted on the cable by each respective surface autonomous vessel.

This provides an improved solution for seismic prospecting in aquatic mediums.