Bogs are acid peatlands supporting specialised flora and fauna, fed predominantly by rain water. They require water-logging for peat formation and this peat acts as a carbon sink. Bogs require permanently waterlogged conditions for peat to form and accumulate from dead plant material that only partially decomposes. Decomposition is unable to fully take place because the lack of oxygen prevents the action of micro-organisms and this peat acts as a carbon sink. 
                                                                                 

Active sphagnum bog

Bog vegetation is characterised by Sphagnum bog mosses, Cotton-grasses, Cross-leaved Heath and Heather. Sundews (below), Bog Rosemary and Cranberry are also common.
                            
 
There are two types of bog in Cumbria: blanket bogs, which are mantles of peat formed in the uplands over gently undulating hills, on plateaux and in hollows; and lowland raised bogs, which develop in hollows and shallow lakes on low-lying, level ground, near to estuaries or on the floodplains of rivers, where decaying vegetation has built up to form quite obvious raised mounds of peat.

Blanket bogs are important for the populations of many breeding birds which have declined in numbers, including Golden Plover, Dunlin, Curlew, Red Grouse, Black Grouse, Short-eared Owl, Hen Harrier and Merlin. Blanket bogs support a variety of invertebrates, including the Northern Dart moth.

Very extensive areas of blanket bog are found on the North Pennine and Lake District Fells, including Moorhouse and Upper Teesdale National Nature Reserve (NNR), Butterburn Flow NNR at Geltsdale, Skiddaw fells, Haweswater and Shap fells, and Armboth Fell.

Cumbria is one of the most important areas in England for lowland raised bog. Large areas are found on the coastal plains of the Solway and Duddon estuaries and around Morecambe Bay. Raised bogs can also be found inland, though usually in more confined and hence smaller sites.

Lowland raised bogs support a unique invertebrate grouping, which includes uncommon species such as the Large Heath butterfly, White-faced Dragonfly or Darter, Downy Emerald dragonfly and the Bog Bush-cricket, as well as a large number of moths. A number of birds are associated with lowland raised bogs, including Curlew and Snipe. Raised bogs provide one of the last refuges for Nightjar in Cumbria.

Lowland raised bogs include the South Solway Mosses National Nature Reserve (NNR) and Drumburgh Moss Cumbria Wildlife Trust (CWT) reserve on the Solway Plain. In the south of the county the most extensive sites are Roudsea Wood and Mosses NNR, the Duddon Mosses NNR, and Foulshaw Moss and Meathop Moss CWT reserves.

The peat in lowland raised bogs and blanket bogs are major carbon sinks as they trap carbon in the un-decomposed vegetation. If peat bodies are damaged the peat starts to dry out and carbon is released into the atmosphere contributing to climate change. The maintenance and restoration of bogs is therefore an important action to help reduce climate change impacts.