In Dalarna and north of it, the border usually follows the drainage divide in the Scandinavian Mountains between rivers that flow to the Norwegian Sea or Skagerak and rivers flowing to the Baltic Sea. Exceptions to this are Rogen and Lierne which are not located on the same of the border as the drainage divide. South of Dalarna, the border in part follows local drainage divides, but also across lakes and along rivers. Some border marks were placed on small lake islands so that they got divided by the border.