The invention concerns an assembly for installation of an underwater structure on the sea floor, said sea floor being covered with particles capable of being driven in suspension in the water above said sea floor, the mounting of said underwater installation capable of being implemented by an underwater robot driven by propulsion means, said propulsion means being capable of displacing the sea floor water and said suspended particles around said installation; said assembly comprising means (22, 26) for covering said sea floor surrounding said installation with a protective blanket (10) adapted to confine said particles on said sea floor.