CMAS Belgium was founded in 1957. It is a founding member of CMAS (Confédération Mondiale des Activités Subaquatiques).

Almost all Belgian sport divers are members. Since 1978, the federation has been split into two leagues: NELOS (Nederlandstalige Liga voor Onderwateronderzoek en -Sport) is the league that groups all Flemish-speaking clubs. LIFRAS (Ligue Francophone de Recherches et d’Activités Sous-Marines) is the league that groups all French-speaking clubs. The clubs (nearly three hundred) affiliated to NELOS or LIFRAS deliver CMAS-recognized diving licenses and are thus recognized worldwide.