Abstract: An improved marine drilling barge for use in ice-covered water is disclosed. The barge has, besides a conventional moon pool through which conventional marine drilling operations can proceed, a roughly circular polygonal hull plan, with an elevation of two truncated pyramid sections joined through their theoretical apices by a vertical walled matching polygonal section. The flat bottom of the hull, to or through which mooring lines are attached to anchor the barge, has an exterior guard member fastened thereto and surrounding the points at which the mooring lines attach or come closest to the hull. The barge is ballasted to achieve downward breaking action by the hull on the ice cover as the latter encroaches on the barge. The proportions of the hull combine with those of the guard member to ensure that the ice broken from the ice cover is deflected to avoid fouling the mooring lines while the maximum draft of the barge is no greater than 20 meters.