Oster (river)

{{Hatnote|Not to be confused with the river Ostyor, a tributary of the Sozh}}

{{Infobox river

| name = Oster, Остер

| image = Oster (Fluss).png

| image_caption = The watershed of the Oster

| mapframe = yes

| mapframe-zoom = 7

| source1_location = Chernihiv Oblast

| mouth = Desna

| mouth_coordinates = {{coord|50.936|N|30.8478|E|source:kolossus-dewiki|display=it}}

| subdivision_type1 = Country

| subdivision_name1 = Ukraine

| length_km = 199

| source1_elevation =

| discharge1_avg = 3,2 m³/s

| basin_size_km2 = 2,950

| progression = {{RDesna}}

| extra =

}}

The Oster ({{Langx|uk|Остер}}) is a river in the northern Ukrainian oblast of Chernihiv. The river is a left tributary of the Desna River. It is approximately 199 km long and its basin area is 2,950 km². It is connected by canals and streams with the Trubizh River, which flows southwest from Kyiv into the Dnieper River. Important towns and villages on the river include: Nizhyn, Kozelets, Roslavl and Oster.{{cite web|url=http://bse.sci-lib.com/article085488.html|title=Остёр (река в Черниговской обл.)|publisher=Большая Советская Энциклопедия|accessdate=2019-05-10|language=ru}}{{cite web|url=http://www.poezdnik.kiev.ua/reki/oster/oster.html|title=Остер|publisher=Водный туризм Украины|year=2002|language=uk|accessdate=2019-05-10}}{{cite web|url=http://okt.kmf.uz.ua/ftt/oktat-ftt/Foldrajz_szak/Ukrajna_termeszeti_fodrajza/szotarukrfoldr.pdf|title=NÉVJEGYZÉK-SZÓTÁR az UKRAJNA TERMÉSZETI FÖLDRAJZA tantárgyhoz|publisher=II. Rákóczi Ferenc Kárpátaljai Magyar Főiskola|accessdate=2019-05-10|format=pdf|language=hu}}