There are some people that enjoy underwater photography so much that they decide to do it professionally. If it is something you are good at then I would be the first to say, grab the chance.
It does take a lot of guts to have your work in the public eye but if you work hard to gain experience then it will pay off for you. I cannot stress the fact that all you can do to improve work quality is to keep practising. You can never practice too much and professionals do spend years honing their photography skills until they are completely happy with all final results.