Device for underwater dry-welding of an area of an area of an underwater structure arranged in a water mass, the device comprising a housing to be removably attached to the underwater structure, the housing comprising: - a welding chamber, the welding chamber comprising a first side having an opening arranged to face the underwater structure when the housing is attached to the underwater structure; - a seal arranged around the opening in the housing configured to seal the housing relative to the underwater structure; - at least one working tool (40, 42) to be manipulated by a diver for working on the area to be welded, the at least one working tool comprising at least a welding torch; - a gas supply connected to the housing and configured to supply gas to the welding chamber thereof; - a water exhaust configured to allow water to be discharged from the welding chamber; wherein the gas supply and water exhaust are configured to dewater at least a part of the welding chamber so as to provide therein an essentially dry environment; - one or more manipulation elements (36 1,36 2,36 3) configured to allow the diver to manipulate the at least one working tool from a position outside the housing; wherein the housing further comprises a second side comprising a transparent window arranged to allow a diver to see both the area to be welded and the at least one working tool (40, 42) to be manipulated; characterized in that the device further comprises a gas exhaust configured to allow gas to be discharged from the welding chamber, the gas exhaust comprising a conduit (21, 22) connected to the upper part of the housing and having an inlet opening in connection with the interior of the welding chamber and an outlet opening at its free end, wherein the outlet opening is positioned at a height position between the height position of the top of the housing and the bottom of the housing - a welding chamber, the welding chamber comprising a first side having an opening arranged to face the underwater structure when the housing is attached to the underwater structure; - a seal arranged around the opening in the housing configured to seal the housing relative to the underwater structure; - at least one working tool (40, 42) to be manipulated by a diver for working on the area to be welded, the at least one working tool comprising at least a welding torch; - a gas supply connected to the housing and configured to supply gas to the welding chamber thereof; - a water exhaust configured to allow water to be discharged from the welding chamber; wherein the gas supply and water exhaust are configured to dewater at least a part of the welding chamber so as to provide therein an essentially dry environment; - one or more manipulation elements (36 1,36 2,36 3) configured to allow the diver to manipulate the at least one working tool from a position outside the housing; - one or more manipulation elements (36 1,36 2,36 3) configured to allow the diver to manipulate the at least one working tool from a position outside the housing; wherein the housing further comprises a second side comprising a transparent window arranged to allow a diver to see both the area to be welded and the at least one working tool (40, 42) to be manipulated;