The small river called Smutná (Unhappy) is the right tributary of the Lužnice river (in the town Bechyně). It springs near the village Chyšky north of the town Milevsko.
Smutná is 44 km long and it watercourse heads south all the way.
A lot of remains of prehistoric burial mounds can be seen along the river. The name of the river originates from that time.