Naerincheon River, the only river that flows north in Korea, crosses Hongcheon and Inje. The name "Naerin" ('cheon' means small river in Korean) is a compound word: 'Nae' is from Hongcheon-gun's "Nae"-myeon area and 'Rin’ from Inje-gun’s "rin"-myeon area. Above the river are many fantastic rocks and stones, and the water that runs along the valley is so pure that you can clearly see the sand and pebbles at the bottom. Naerincheon Gyegok Valley starts near Mt. Odaesan Valley and Hapganggyo Bridge and continues on for about 57 km. Since the range is so long, it is hard to pinpoint Naerincheon. Usually, when people say Naerincheon, they mean the downstream of Naerincheon. The upper stream of Naerincheon is again divided into Misan Valley or Moraeso Valley. Few people go there because it is hard to reach. On the upper stream of Bangtaecheon, which joins together with Naerincheon, is Jindong Valley, and to the north of Naerincheon is Mt. Jumbongsan, Mt. Bangtaesan, Bangdong Springs, and Mt. Bangtaesan Recreational Forest. Also, there are Hwangso and Seori Resorts in the mid-section of Naerincheon, and Piasi Valley downstream. Piasi is the area around Gosa-ri, Inje-eup. Piasigang River is the water stream between Hyeon-ri and Soyangho Lake. These are the most popular places. Around the water stream of Naerincheon, there are many mountains and branch streams. Wide woods and rocks are here, and are very attractive to families that visit here to play water sports, fishing and camping.