Oacoma is a town in Lyman County, South Dakota, United States. The population was 386 at the 2020 census. Oacoma is located on the west bank of the Missouri River, across from Chamberlain.
Wikipedia https://en.wikipedia.org/wiki/Oacoma,_South_Dakota
Coordinates 43°47'45.992" N -99°23'43.188" E