One of the worldwide organizations that offers courses is Global Underwater Explorers. There are others as well. However, this is one of the premier organizanizations and their courses are well recognized in most parts of the world.
One can also train under a professional. This is for those who wish to avoid formal qualifications and begin making some money soon after starting.
Love for the waters, an adventure seeking spirit and the desire to make a handsome income while having plenty of time for leisure.
In some countries the pay is as high as 1200 USD per day and in many others it averages out to around 500 USD per day.
For Job Opporunity seek here.