The Velký močál - Great Swamp is a raised peatbog in the Krušné hory mountain range which is almost completely untouched by peat extraction. The peatbog covers an area of 50.27 ha at elevations of 910 – 930 metres in the parish of Rolava. The NNR, which was declared in 1969, covers almost all of the stages of development of peatbogs – from deep pools through bog hollows and hummock communities, shrub growths to the final stage – growths of bog pine scrubs (Pinus x pseudopumillo) on the stabilized raised bog.
Velký močál NNR is one of the largest peatbogs in the Rolava unit. The basement and surrounding lie on coarse-grained biotite granite of the Krušnohorský type. The rock basement is only exposed as small boulder outcrops on the erosional slopes of the stream which flows from the south-east tip of the peatbog. The soil mantle varies between 1 and 2 metres in thickness.
The peatbog is a textbook example of a montane (watershed) raised bog. It has an irregular shape with a greatest thickness of the peat layer of 670 cm and an average thickness of 216 cm. Numerous water-filled pools can be found in the north-western tip and in the centre of the reserve.
The moss layer is represented all over the bog by the sphagnum mosses – Sphagnum robustum and Sphagnum recurvum, as well as the common hair cap (Polytrichum commune). The herb layer includes peatbog species such as bilberry (Vaccinium myrtillus), hare’s-tail cottongrass (Eriophorum vaginatum), bog whortleberry (Vaccinium uliginosum), the cranberry Oxycoccus palustris and crowberry (Empetrum nigrum).
Interesting and rare species also include the bog sedge (Carex limosa), and Rannoch rush (Scheuchzeria palustris) as well as the carnivorous species - great sundew (Drosera anglica) and round-leaved sundew (Drosera rotundifolia).
The fauna at Velký močál NNR is formed of the typical species for montane raised bogs. The mammals include red deer (Cervus elaphus), roe deer (Capreolus capreolus), wild boar (Sus scrofa) and common shrew (Sorex araneus). Significant populations of capercaillie (Tetrao urogallus) and black grouse (Tetrao tetrix) live in the area around the peatbogs. Other more common birds which have been observed on the territory include the green sandpiper (Tringa ochropus), honey buzzard (Pernis apivorus), hobby (Falco subbuteo), wryneck (Jynx torquilla), meadow pipit (Anthus pratensis), snipe (Gallinago gallinago), red-backed shrike (Lanius collurio), great grey shrike (Lanius excubitor), buzzard (Buteo buteo), crossbill (Loxia curvirostra), and the teal (Anas crecca) by the water surfaces.