Professional diving is underwater diving where the divers are paid for their work. Occupational diving has a similar meaning and applications. The procedures are often regulated by legislation and codes of practice as it is an inherently hazardous occupation and the diver works as a member of a team. Due to the dangerous nature of some professional diving operations, specialized equipment such as an on-site hyperbaric chamber and diver-to-surface communication system is often required by law, and the mode of diving for some applications may be regulated.
There are several branches of professional diving, the best known of which is probably commercial diving and its specialised applications, commercial offshore diving, inshore civil engineering diving, marine salvage diving, hazmat diving, and ships husbandry diving. There are also applications in scientific research, marine archaeology, fishing and aquaculture, public safety, law enforcement, military service, media work and diver training.