Muskeg (Ojibwe: mashkiig; Cree: maskīk; French: fondrière de mousse, lit. moss bog) is an acidic soil type common in Arctic and boreal areas, although it is found in other northern climates as well. Muskeg is approximately synonymous with bogland, but "muskeg" is the standard term in Western Canada and Alaska, while 'bog' is common elsewhere. The term became common in these areas because it is of Cree origin; maskek (ᒪᐢᑫᐠ) meaning low-lying marsh. Large tracts of this soil existing in Siberia may be called muskeg or bogland interchangeably.
Muskeg consists of dead plants in various states of decomposition (as peat), ranging from fairly intact sphagnum moss, to sedge peat, to highly decomposed humus. Pieces of wood can make up five to fifteen percent of the peat soil. Muskeg tends to have a water table near the surface. The sphagnum moss forming it can hold fifteen to thirty times its own weight in water, allowing the spongy wet muskeg to form on sloping ground. Muskeg patches are ideal habitats for beavers, pitcher plants, agaric mushrooms and a variety of other organisms.