The Cercles des Naturalistes de Belgique (CNB) is a nature-focused organisation working to help people reconnect with the natural world through discovery, education and conservation. Active in Wallonia, its local volunteer circles organise guided outings and activities for the public, while the organisation also offers programmes for participants of different ages and levels of experience.

Its activities include nature walks, expert-led field days, themed lessons, multi-day residential or itinerant courses, and events exploring wildlife, plants and ecology. CNB provides long-form training in natural sciences and environmental topics, including its Guide-Nature® programme, as well as school programmes and training tailored to specific requests. Astronomy is another area of activity, with sky observations, introductory sessions, overnight experiences, courses and gatherings at the Centre Ardenne Observatory.

CNB shares news and learning resources about biodiversity and natural environments, and supports participation through membership and volunteer opportunities. Its Nature Shop, run with the Ligue Royale Belge pour la Protection des Oiseaux, offers more than 4,500 products for observing and protecting wildlife.