|• Revised Romanization||Gosan-gun|
Map of Kangwon showing the location of Kosan
|Administrative divisions||1 ŭp, 24 ri|
The county is largely mountainous. The central area forms a basin. The county's highest point is Chuaesan. Major streams include the Namdaech'ŏn, Ryongjiwŏnch'ŏn, and Namsanch'ŏn. There are a total of 13 reservoirs. Forestland makes up some 63.8% of the county's area.
Agriculture dominates local industry in Kosan, with crops including rice, maize, millet, wheat, barley, soybeans, and red beans. The region is particularly noted for its abundant production of fruit.
Mining is widely developed, exploiting the local deposits of gold, silver, copper, iron, limestone, lead, zinc, gypsum, and other minerals.