Ybbs

{{For|the town|Ybbs an der Donau}}

{{Infobox river

| name = Ybbs

| image = Ybbs.JPG

| image_caption = The Ybbs near Amstetten

| source1_location = near Mariazell

| source1_coordinates = {{coord|47.7603|N|15.2053|E|source:kolossus-dewiki|display=inline}}

| mouth_location = Danube in Ybbs an der Donau

| mouth_coordinates = {{coord|48.1701|15.1023||display=it}}

| progression = {{RDanube}}

| subdivision_type1 = Country

| subdivision_name1 = Austria

| subdivision_type2 = State

| subdivision_name2 = Lower Austria

| length = {{convert|133.9|km|abbr=on}} {{GeoQuelle|AT-3|NÖA}}

| source1_elevation = 262m

| discharge1_avg =

| basin_size = {{cvt|1291|km2}}

}}

Ybbs ({{IPA|de|ˈɪps|-|De-Ybbs.ogg}}) is a river in Lower Austria. Its drainage basin is {{cvt|1291|km2}}.{{cite web|url=https://info.bmlrt.gv.at/dam/jcr:33699a3d-88fd-4dbc-8081-4d28c80f83bc/Beitrag%2062.pdf|title=Flächenverzeichnis der Flussgebiete: Donaugebiet von der Enns bis zur Leitha|work=Beiträge zur Hydrografie Österreichs Heft 62|page=42|date=December 2014}}

Its source is located on the Zellerrain Pass near Mariazell. In the beginning, the river is called {{lang|de|Weiße Ois}}, then onwards from the border between Lower Austria and Styria up to Lunz am See it is called {{lang|de|Ois}}. From there until its confluence to the Danube at Ybbs an der Donau, it is finally called Ybbs.

The Ybbs has a strongly meandering course and flows for around {{convert|134|km|mi|abbr=on}} from the South in a northward direction. Along the river there are many metal and lumber industry plants.

The most important towns on the Ybbs are Lunz am See, Göstling an der Ybbs, Hollenstein an der Ybbs, Opponitz, Ybbsitz, Waidhofen an der Ybbs, Amstetten, and Ybbs an der Donau.

The valley of the river Ybbs is called: Ybbs Valley, or Ybbs Field ({{langx|de|Ybbsfeld}}). In 788, it was the site of a battle, between Franks and Avars.{{sfn|Pohl|2018|pp=378}}