The Ondava is a 146.5 km long 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...

 in Slovakia

Slovakia

The Slovak Republic is a landlocked state in Central Europe. It has a population of over five million and an area of about . Slovakia is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south...

, the northern source river of the Bodrog

Bodrog

The Bodrog is a river in eastern Slovakia and north-eastern Hungary. It is a tributary to the river Tisza. The Bodrog is formed by the confluence of the rivers Ondava and Latorica near Zemplin in eastern Slovakia...

. Its source is in the Low Beskids

Low Beskids

The ', ', Low Beskids or Lower Beskids is one of the Beskids mountain ranges in the Outer Eastern Carpathians in southeastern Poland and northeastern Slovakia...

 (Eastern Carpathian Mountains

Carpathian Mountains

The Carpathian Mountains or Carpathians are a range of mountains forming an arc roughly long across Central and Eastern Europe, making them the second-longest mountain range in Europe...

), near the village Nižná Polianka

Nižná Polianka

Nižná Polianka is a village and municipality in Bardejov District in the Prešov Region of north-east Slovakia.-Geography:The municipality lies at an altitude of 395 metres and covers an area of 5.876 km².It has a population of about 252 people....

, close to the border with Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

. The Ondava flows south through the towns Svidník

Svidník

Svidník is a town in eastern Slovakia, acting as the capital of Svidník District in Prešov Region. It has a population of 12,384 .-Geography:...

, Stropkov

Stropkov

Stropkov is a town in Stropkov District, Prešov Region, Slovakia.-History:Stropkov is an economical, social and cultural centre of north Zemplín...

 and Trhovište

Trhovište

Trhovište is a village and municipality in Michalovce District in the Kosice Region of eastern Slovakia.-Geography:The village lies at an elevation of 130 metres and covers an area of 12.562 km²...

, and through the Ondavská Highlands

Ondavská Highlands

The Ondavská Highlands is a mountain range in the Prešov Region of Slovakia, named for the Ondava River. The mountains are part of the Lower Beskids ranges , which are in turn part of the Outer Eastern Carpathians.The mountains are characterized by gentle ridges, mostly wooded in...

.

Near the village Cejkov

Cejkov

Cejkov is a village and municipality in the Trebišov District in the Košice Region of eastern Slovakia.-Geography:The village lies at an altitude of 172 metres and covers an area of 20.845 km².It has a population of about 1210 people.-Facilities:...

, the Ondava joins the Latorica and forms the Bodrog

Bodrog

The Bodrog is a river in eastern Slovakia and north-eastern Hungary. It is a tributary to the river Tisza. The Bodrog is formed by the confluence of the rivers Ondava and Latorica near Zemplin in eastern Slovakia...

 river, itself a tributary of the Tisza

Tisza

The Tisza or Tisa is one of the main rivers of Central Europe. It rises in Ukraine, and is formed near Rakhiv by the junction of headwaters White Tisa, whose source is in the Chornohora mountains and Black Tisa, which springs in the Gorgany range...

. The Ondava river is 44% regulated.

Tributaries

• Major left tributaries – Mirošovec, Ladomírka, Chotčianka, Brusnička, Oľka
  Olka
  Oľka is a village and municipality in the Medzilaborce District in the Prešov Region of far north-eastern Slovakia.-Geography:The municipality lies at an altitude of 250 metres and covers an area of 31.459 km². It has a population of about 350 people....
  
   and Ondavka
  Ondavka
  Ondavka is a small village and municipality in Bardejov District in the Prešov Region of north-east Slovakia.-Geography:The municipality lies at an altitude of 480 metres and covers an area of 3.468 km².It has a population of about 34 people....
  
  .
• Major right tributary - Topľa river
  Topla River
  The Topla River is a tributary of the Bega River in Romania.-References:* Administraţia Naţională Apelor Române - Cadastrul Apelor - Bucureşti* Institutul de Meteorologie şi Hidrologie - Rîurile României - Bucureşti 1971...
  
  .
  • Minor right tributaries - Olšavanka and Trnávka
    Trnávka
    Trnávka is name of several locations in central Europe:*Trnávka - Czech Republic* Trnávka, a village in the Pardubice Region of the Czech Republic...
    
    .