| Nahavaq | |
| Also Known As: | South West Bay, Siesip |
| Region: | Malekula |
| States: | Vanuatu |
| Ethnicity: | 860 ethnic population (no date) |
| Speakers: | 600 |
| Date: | 2001 |
| Ref: | e25 |
| Familycolor: | Austronesian |
| Fam2: | Malayo-Polynesian |
| Fam3: | Oceanic |
| Fam4: | Southern Oceanic |
| Fam5: | North-Central Vanuatu |
| Fam6: | Central Vanuatu |
| Fam7: | Malakula |
| Fam8: | Malakula Coastal |
| Iso3: | sns |
| Glotto: | sout2857 |
| Glottorefname: | Nahavaq |
| Map: | Lang Status 99-NE.svg |
Nahavaq, also known as South West Bay (Malekula) or Siesip, is one of the many languages of the Malekula Coast group of Vanuatu.