Overall, nearly 50% of Bosnia and Herzegovina is forested. Most forest areas are in the centre, east and west parts of Bosnia. Herzegovina has a drier Mediterranean climate, with dominant karst topography. Northern Bosnia (Posavina) contains very fertile agricultural land along the Sava river and the corresponding area is heavily farmed. This farmland is a part of the Pannonian Plain stretching into neighboring Croatia and Serbia. The country has only 20 kilometres (12 miles) of coastline, around the town of Neum in the Herzegovina-Neretva Canton. Although the city is surrounded by Croatian peninsulas, by international law, Bosnia and Herzegovina has a right of passage to the outer sea.