The Channel coastline is 65 kilometres long. Land along the coast has been reclaimed from the sea using polders and dikes. Much of Belgium is relatively flat but the Ardennes in the southeast are forested and hilly with steep river valleys. The rivers which flow through Belgium include the Scheldt, the Sambre and the Meuse. The climate is temperate, with warm summers and cool winters.
Rainfall is possible throughout the year.
The population density in Belgium is among the highest in the world, but the country does include wild, forested hills in the Ardennes. Other environments within the country include heathlands along the border with Holland, a high moorland plateau with peat bogs in the Northern Ardennes on the German border and reclaimed land along the North Sea coasts. Like most countries with coal and steel industries, Belgium has suffered considerably from environmental pollution. Industrial waste and fertilizer run-off from farmed areas have polluted the rivers severely. EU finance has assisted some of these initiatives.