Commercial diving covers many areas, mainly if you get paid for performing a task underwater that is not recreational, then it is commercial diving. It encompasses things such as cutting, welding, cleaning, taking seabed samples and yes, occasionally we get to raise boats from the sea bed. Saftey work mainly takes place in the middle of the ocean working on gas and oil installations. The money is great, the work is not. Lots of boredom, being cold and generally uncomfortable. As a safety diver, I can be suited and ready to go into the water for 6 hours at a time. That means in a dry suit, standing around on the boat ready to hit the water at a moments notice. The cost of the courses, well, if you have a few thousand pounds then your good. The basic scuba course for commercial divers is just under 2000 pounds and trains you to cmas *** / divemaster with efr training. It teaches comms and full face diving and a whole load of other things. More info on the course can be found at
www.puffin.org on the HSE training pages.
Good luck with your future. Happy bubbles.
Peter