 Certification relates to a set of skills and knowledge defined by the associated training standard, which also specifies the limitations on the scope of diving activities for which the diver is deemed competent.These limitations involve depth, environment and equipment that the diver has been trained to use.Marketing of scuba diving tourism is generally by advertising in specialist and general tourism magazines, both print and web based, at trade shows, on websites, and by personal communications from satisfied customers to their acquaintances with similar interests.