Smagne

{{Short description|River in France}}

{{Infobox river

| name = Smagne

| image =

| image_caption =

| pushpin_map = France#France Pays de la Loire

| source1_location = Bourneau

| source1_coordinates= {{coord|46|33|13|N|00|49|40|W}}

| mouth_location = Lay

| mouth_coordinates = {{coord|46|32|13|N|01|11|57|W|display=inline,title}}

| subdivision_type1 = Country

| subdivision_name1 = France

| length = {{convert|50.3|km|mi|abbr=on}}

| source1_elevation = {{convert|105|m|ft|abbr=on}}

| mouth_elevation = {{convert|7|m|ft|abbr=on}}

| discharge1_avg = {{convert|1.54|m3/s|cuft/s|abbr=on}}

| basin_size = {{convert|190|km2|sqmi|abbr=on}}

| progression = {{RLay}}

}}

The Smagne ({{IPA|fr|smaɲ}}) is a {{convert|50.3|km|mi|adj=mid|-long}} river in the Vendée département, western France.{{Sandre|id=N32-0300|nom=Smagne}} Its source is near Bourseguin, a hamlet in Bourneau. It flows generally west. It is a left tributary of the Lay into which it flows between Bessay and Mareuil-sur-Lay-Dissais.