An Area of Natural and Scientific Interest (or ANSI) is an official designation by the provincial Government of Ontario in Canada applied to contiguous geographical regions within the province that have geological or ecological features which are significantly representative provincially or regionally. Three separate designations exist: Life Sciences (or Life Sciences ANSI, or ANSI-LS), a region exhibiting ecological features; Earth Sciences (or Earth Sciences ANSI, or ANSI-ES), a region exhibiting geological features; and Candidate, a region under consideration for such a designation. Some sites with this designation were assessed through the International Biological Program between 1964 and 1974.
Regions classified as Areas of Natural and Scientific Interest are subject to certain management constraints. Ultimately, land management and stewardship is a municipal responsibility, so that "decisions on the appropriate levels of protection and land uses are the responsibility of the local municipality". Each region is specified to be either regionally or provincially significant for its representative feature.