Underwater welding is one of the most dangerous occupations.
Underwater, the odds are stacked against you. The pressure threatens to crush the body. Clouds of bubbles making any task difficult to perform by blocking visuals. Despite the dangers, thousands take on the responsibility of installing underwater structures. Underwater welders are responsible for repairing pipelines, offshore oil drilling rigs, ships, dams, locks, sub-sea habitats and nuclear power facilities, to name a few.
Hope this helps!
But you will be in weightless, you will have to be comfortable with breathing on a respiratory underwater, you may or not be able to see in front of you depending on how murky it gets, and of course not scared of fish.
But I would assume there is specific equipment that you will be using and lugging around down there.
I would look into doing a scuba class and when you're under the water think about doing the job. im sure you can ask the suba place you go to how to pursue this further.