Bogs are wet, peat-producing ecosystems. Peat is formed when dead plant parts decompose slowly in wet, cold and low-oxygen soil. Over time, the plant matter is concentrated into peat. This is how the bog's vegetation creates its own soil. In Finnish bogs, peat is formed at a rate of approximately 0,5 mm per year. This means that the peat layer of a 8 000-year-old bog can be approximately four meters deep.

Finland is a relatively flat country with a wet and cold climate. The amount of rainfall exceeds the amount of water that is evaporated back into the atmosphere. This water can accumulate in pools and depressions that were created during the last ice age. This explains why bogs are so common in Finland. They comprise almost one third of the nation's land surface area. This makes Finland the most boggy nation on the planet.

The number of bogs differs between various regions of Finland. Bogs are the most common in Northern Ostrobothnia, Kainuu, Koillismaa and Southern Lapland. In contrast, bogs are more rare in Southern Finland.


A pine swamp is a type of bog characterized by the presence of pine trees.