| Nay Aru | |
| Subdivision Type1: | Country |
| Subdivision Name1: | Sri Lanka |
| Subdivision Type2: | Province |
| Subdivision Name2: | Northern Province |
| Subdivision Type3: | Districts |
| Subdivision Name3: | Vavuniya, Mannar |
| Length: | 40km (30miles) |
| Source1 Location: | Vavuniya District |
| Mouth: | Palk Bay |
| Basin Size: | 560km2 |
The Nay Aru (or Nai Aru) is a river in Northern Province, Sri Lanka. The river rises in south-west Vavuniya District, before flowing north/north-west through Vavuniya District and Mannar District. The river empties into Palk Bay.[1]