Pikunis
The Mandan Indians knew of cataracts and called them by a descriptive (but not formal) name: "Minni-Soze-Tanka-Kun-Ya", or "the great falls." The South Piegan Blackfeet, however, had a formal name for Rainbow Falls and called it "Napa's Snarling." No record exists of a Native American name for any of the other four waterfalls.