The Sutla or Sotla (Slovene) is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 flowing through Slovenia

Slovenia

Slovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of...

 and Croatia

Croatia

Croatia , officially the Republic of Croatia , is a unitary democratic parliamentary republic in Europe at the crossroads of the Mitteleuropa, the Balkans, and the Mediterranean. Its capital and largest city is Zagreb. The country is divided into 20 counties and the city of Zagreb. Croatia covers ...

, mostly forming their border. It is a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 to the Sava, itself a tributary to the Danube

Danube

The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....

.
It is 92 km (57.2 mi) and it has a watershed area of 582 square kilometre.

The Sotle provincial park is located on the banks of this river. The Sutla flows through the following municipalities:

• in Slovenia: Rogatec
  Rogatec
  Rogatec is a small town and a municipality in eastern Slovenia, on the border with Croatia. The area traditionally belonged to the region of Styria. It is now included in the Savinjska statistical region....
  
  , Rogaška Slatina
  Rogaška Slatina
  Rogaška Slatina is a settlement and a municipality in Slovenia. It is famous for its curative mineral water, spa and crystal glass.Rogaška Slatina is a synonym for health resort tourism in Slovenia. For centuries the curative mineral water rich in magnesium , the picturesque countryside and other...
  
  , Podčetrtek
  Podcetrtek
  Podčetrtek is a settlement and a municipality in eastern Slovenia. It was first mentioned as a settlement in the early 11th century as Lonsperch and later as Lontsperch, Landsprech, Landsperg, Landsberg and eventually Windisch Landsberg. Its Slovene name is a reference to Thursday , which was the...
  
  , Bistrica ob Sotli
  Bistrica ob Sotli
  Bistrica ob Sotli is a settlement and municipality in eastern Slovenia. It has been an independent municipality since 1999. The settlement itself lies on a river terrace above the right bank of the river Sotla. The area traditionally belonged to the region of Lower Styria...
  
  , Brežice
  Brežice
  Brežice is a city and municipality in eastern Slovenia in the Lower Sava Valley, near the Croatian border. The area was traditionally divided between Lower Styria and Lower Carniola...
  
  
• in Croatia: Đurmanec, Hum na Sutli
  Hum na Sutli
  Hum na Sutli is a town in the Krapina-Zagorje County of Croatia. According to the 2001 census, there are 5,476 inhabitants in the settlement, the absolute majority of which are Croats....
  
  , Desinić
  Desinic
  Desinić is a village and municipality in the Krapina-Zagorje County in Croatia. According to the 2001 census, there are 3,478 inhabitants in the area, absolute majority which are Croats.-See also:* Veliki Tabor Castle...
  
  , Zagorska Sela
  Zagorska Sela
  Zagorska Sela is a village and municipality in Krapina–Zagorje County in Croatia. According to the 2001 census, there are 1,197 inhabitants in the area, absolute majority which are Croats....
  
  , Klanjec
  Klanjec
  Klanjec is a small town in northwestern Croatia, in the region of Hrvatsko Zagorje on the border with Slovenia. The population of Klanjec is 565, but there are 2,915 people in the municipality...
  
  , Kraljevec na Sutli
  Kraljevec na Sutli
  Kraljevec na Sutli is a village and municipality in Krapina-Zagorje county in Croatia. According to the 2001 census, there are 1,815 inhabitants in the area, absolute majority which are Croats....
  
  , Brdovec

The hydrological parameters of the Sutla are regularly monitored in Croatia at Zelenjak.