What welding has to be done at 300 feet? Only thing I can think of is a platform and you'd think they could find a better way maybe by lowering it as they go. There has to be a good reason to pay big money and put a man in jeopardy.

I am pretty sure oil rigs require deep drilling.

Milt,

Deep water welding is usually repair welding. That is primarily off shore platform work and in some parts of the world, pipeline welding. Some of this stuff is done in the North Sea. Just going to the North Sea in the wrong time of the year is taking your life in your hands, much less diving there! I think the combo of "you-can't-come-up-fast" and the "eventually-your-body-can't-take-it-any-longer" are the things that combine wto provide you with a shortened life.