 Erto e Casso borders the municipalities of Castellavazzo, Cimolais, Claut, Longarone, Ospitale di Cadore, Perarolo di Cadore, Alpago and Soverzene.All the bordering municipalities, except Cimolais and Claut, are part of the nearby Province of Belluno, in Veneto.The "comune" is composed by the main settlements of Erto, the administrative seat, and Casso.