The Čepkeliai Marsh (Lithuanian: Čepkelių raistas) is the largest bog (a mire) in Lithuania.

Located in Varėna District Municipality, south of Marcinkonys village and north of Kotra River, which flows along the Belarus–Lithuania border in this area.

The area of the swamp is protected as a state nature reserve (Čepkēliai Reserve), with its administration in Marcinkonys,[3] and part of the cross-border wetlands of international importance: Kotra-Cepkeliai Transboundary Ramsar Site established in 2010.

The reserve is a sanctuary for cranes, white-tailed eagles, black grouses, heather cocks, mountain hares, martens, smooth snakes.

[3] Cranberry and mushroom picking is allowed for 10 days in early September for residents of the nearby villages with a permit, for personal use only.