The county is primarily mountainous, and is traversed by the Masingryŏng and Kwangju ranges. There are numerous mountains outside of these two ranges as well. The chief streams include the Namdaech'ŏn, Yongjich'ŏn, and Komitanch'ŏn (고미탄천). 75% of the county's area is occupied by forestland.
Administrative divisions
Sep'o county is divided into 1 ŭp (town), 1 rodongjagu (workers' district) and 24 ri (villages):
Sep'o-ŭp
Changch'ol-lodongjagu
Chŏngdong-ri
Chungp'yŏng-ri
Chungsam-ri
Ch'ŏn'gi-ri
Ch'up'yŏng-ri
Kisal-li
Naep'yŏng-ri
Paeksal-li
Pokmal-li
Pukp'yŏng-ri
Rimong-ri
Sambang-ri
Sangsul-li
Sindong-ri
Sinsaeng-ri
Sŏha-ri
Songp'o-ri
Sŏngp'yŏng-ri
Sŏngsal-li
Taegong-ri
Taemul-li
Wŏnnam-ri
Yaksu-ri
Yuyŏl-li
Economy
Sep'o is host to deposits of molybdenum, silver, zinc, and fluorite. Agriculture also contributes to the local economy; Sepo is particularly known for its radishes. In addition, livestock raising and orcharding play a role, and there is some small-scale manufacturing as well.