The Duino Cliffs Nature Reserve (Riserva naturale delle Falesie di Duino) extends over 107 hectares, providing a biodiversity that creates a unique landscape, defined by its steep white limestone coastal cliffs. 

Inside the Reserve, the famous Rilke Trail leads from Sistiana to Duino Castle, through lush continental vegetation. The landscape includes woods and Mediterranean scrub, with holly oaks, hornbeams and bushes.

A variety of sedentary birds nest here, near reptiles such as snakes, adders and lizards: the herring gull, the common raven and the peregrine falcon, which is an endangered species.