The Stará Řeka (Old River) is the original bed of the Lužnice river near the town Třeboň.
There is a protected area of the same name along the river. It is the largest nature reserve of the Protected Landscape Area Třeboňsko (1,200 ha). The marshlands, morasses and wet meadows with many species of plants and herbs form most of this area.

The reserve stretches from the small village Majdalena near the place, where the Nová Řeka canal (New River) branches out of the Lužnice river, to the inflow into the Rožmberk pond. Access to the reserve is possible along the road from Třeboň to the small town Stráž nad Nežárkou, turning-off right in the small village Stará Hlína. The red or yellow marked paths lead to the reserve from Třeboň. The circular trail along this signs is about 14 km long.