Abstract: A system for excavating a trench in ground submerged in water is described. The system includes an excavation device comprising moving means capable of moving the excavation device on the submerged ground and excavation means capable of being supplied with pressurized water and excavating the submerged ground using the pressurized water, The system also includes control means configured to control the moving means and supply means configured to supply pressurized water to the excavation means, where the supply means can include at least one water-jet turbine.