it is commenly performed with a stinger and a stick (SMAW).  Because of extreme shock hazards the weld is normally struck/started with the electrode in contact with the joint/material.  Via radio/intercom the welder informes the crew when to make the electrode live/hot(active) and when to make it cold/(inactive).  It is an extermely hazardoes process....due to the hazards of diving combined with welding in a conductive atmorphere.

I knew a fella personnaly that went thru dive school as well as specialized welding training to do offshore work.  He makes a good living but when he is "burining rods" he is risking his life as well as his health every day.