As a marine structural welder, your duties are to install, modify, and repair metal structures in the water, such as metal bridges, offshore oil platforms, or other marine structures. Marine structural welders often work on the assembly or modification of components below the surface of the water, so much of your time is spent diving to assess issues and perform the necessary work using specialized underwater welding equipment. Marine structural welders often travel great distances for work, and you may spend long periods of time in remote locations.