Cannon Ball (Arikara: načiiʾuuháwi [načii’uuháWI], sananaapíkat [sananaapíkAt]; Lakota: Íŋyaŋwakağapi) is a census-designated place (CDP) in Sioux County, North Dakota in the United States and on the Standing Rock Indian Reservation. It sits in the northeastern part of Sioux County where the Cannonball River meets Lake Oahe of the Missouri River.