The Sutla is a river that marks the border between Slovenia and Croatia for almost its entire length . The Sutla is about 92 km long. The rivers catchment area is about 581 km² (of which 451 km² are in Slovenia).
It rises in Slovenia on the southern slopes of Maceljska Gora , below the Pass 715 m, and flows into the Sava River as its left tributary near Savski Marof. The drop in the river flow is 369 m. It receives larger tributaries only from the right side (Mostica, Bistrica and Bizel). It is regulated in its lower reaches. A railway line and a road to Kumrovec pass through the Sutla Valley.
