The Acheron River is a river in the South Island of New Zealand, in Marlborough and flows into the Waiau Toa / Clarence River. It flows southwest and then east for a total of 76 kilometres (47 mi), joining the Waiau Toa / Clarence at the southern end of the Inland Kaikōura mountains. The Alma and Severn Rivers flow into the Acheron before it joins the Waiau Toa / Clarence.

• List of rivers of New Zealand
• Acheron River (Canterbury)
• Acheron (river in Greece)

"Place name detail: Acheron River". New Zealand Gazetteer. New Zealand Geographic Board. Retrieved 29 March 2018.