Bogs are peat-accumulating wetlands that support unique plant communities able to thrive in waterlogged, acid and nutrient-poor conditions. They are largely raised above the influence of groundwater by the accumulation of peat. Over thousands of years, sphagnum mosses, leaves and roots accumulate faster than they can be decomposed, and peat forms.
Peat lands in raised ombotrophic bogs and fens cover nearly a quarter of the park. Some bogs occupy areas of less than one hectare, while others exceed 500 hectares.