| Unorganized South Nipissing District | |
| Official Name: | Nipissing, Unorganized, South Part |
| Flag Size: | 120x100px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Type2: | District |
| Established Title: | Settled |
| Leader Title: | Federal riding |
| Leader Title1: | Prov. riding |
| Area Land Km2: | 6710.22 |
| Population As Of: | 2016 |
| Population Footnotes: | [1] |
| Population Total: | 103 |
| Population Density Km2: | 0.015 |
| Utc Offset: | -5 |
| Utc Offset Dst: | -4 |
| Coordinates: | 45.8333°N -103°W |
Unorganized South Nipissing District is an unorganized area in north-central Ontario, in the District of Nipissing. It is almost entirely within and includes most of Algonquin Provincial Park.
Localities located within the unorganized area are:
The following geographic townships are included:
All, except Boulter, Lauder, and parts of Ballantyne, Boyd and Paxton are within Algonquin Provincial Park.
Most of the population lives outside of Algonquin Park on the northern or northwestern fringes of the region. According to the 2016 Census, the blocks that encompass the Townships of Boulter, Lauder, Pentland and Boyd had a combined population of 57. The area around Loxton Lake in Ballantyne Township (Census Block 35480228012) had a population of 26. Census Block 35480228215 which covers parts of Bronson and Stratton Townships in the Northeast corner of Algonquin Park had a population of 5, while 15 people lived in Census Block 35480228146 which covers most of the western part of the region.