Großer Kranichsee, Nature reserve in Eibenstock and Muldenhammer, Germany.

Großer Kranichsee is a nature reserve in Eibenstock and Muldenhammer located at approximately 950 meters elevation. The protected area features raised bog systems and serves as a natural watershed between two river valleys.

The bog was first placed under protection in 1912, then again in 1961, 1967 and 2008, each time with enlarged boundaries. The 611-hectare reserve is the core of the Natura 2000 site "Erzgebirgskamm am Großen Kranichsee" and part of the EU bird protection area "Westerzgebirge".

The name Kranichsee is linked to the Slavic word granica, meaning border, and older terms for boggy ground, so it reads as "border bog"; a 1791 Saxon survey map labels it "Grosse Cranich See". The bog straddles the German-Czech border: the larger part lies on the Czech side in the Rolavská vrchoviště reserve, while the German reserve holds the smaller share.

Access to the reserve is via marked trails that allow observation of the bog landscape without disturbing sensitive zones. Visitors should wear sturdy footwear and expect wet, boggy terrain conditions.

The name comes from the Slavic word granica (border) and an old term for bog, meaning "border bog". A Saxon survey map of 1791 already labels it "Grosse Cranich See". The Ore Mountain branch at Carlsfeld built a corduroy causeway and a viewing scaffold in 1908; the scaffold was not replaced for cost reasons.