Seltanahunshin is bounded on the north by Doon (Drumreilly) townland, on the south by Tullylackan Beg townland, on the west by Altakeeran and Slievenakilla townlands and on the east by Curraghnabania, Garryfliugh and Knockfin townlands. Its chief geographical features are Sliabh an Iarainn mountain, reaching a height of 1,251 feet, the Yellow River, waterfalls, forestry plantations, small streams and river swallow holes. Seltanahunshin is traversed by minor public roads and rural lanes. The townland covers 819 statute acres.