High Quality Content by WIKIPEDIA articles! Advanced Open Water Diver (AOWD) is a scuba diving certification level provided by several diver training agencies, such as Professional Association of Diving Instructors (PADI), Scuba Schools International (SSI) and Underwater Explorers` Federation. The equivalent course offered by National Association of Underwater Instructors (NAUI) is the Advanced Scuba Diver (which had previously been called OW-II for "Open Water II"). The certification level is roughly equivalent to the CMAS * Diver qualification and the British Sub-Aqua Club (BSAC) Sport Diver qualification, although some differences occur. For example, BSAC Sports Divers are trained in basic decompression diving, something that is strictly forbidden by U.S. based diving certification agencies for Recreational diving.