Hiking in Korea

I love hiking. It is among my favourite things to do. Hiking is very popular in Korea since there are many mountains that are easily accessable. During the nice weather the Seoul subways and buses are filled with people in hiking gear taking the train to their destination. The last time I was in Korea I did some hiking, but not as much as I wished. I went to Namhansanseong (Nam-han-san-sung, and it means "south korean mountain fortress) which is on Line 8. The sunsets from the top are breathtaking. I also went to Bukhansanseong (north korean mountain fortress) as well. If I have it my way, I will climb every major mountain in this country before I am ever through with it. I'll see how much I can get done.
There is a term called "peak bagging" when hikers have a list of mountains to climb and they try to get as many of those peaks climbed as possible. There are special regional clubs just for that. In my area of the USA there is a list of "Four Thousand Footers" (imperial) in the New England area. There is also the Adirondack Forty-Sixers in New York state and many other peak-bagging lists around the world. For an unofficial peak-bagging list for South Korea I have:
1. Seoraksan
2. Hallasan
3. Bukhansan (I only made it halfway because it was getting dark)
4. Suraksan
5. Dobongsan
6. Jirisan
7. Seonunsa
8. Buramsan (that should be easy to do)
9. Manisan
10.Odaesan

I found out about Hwanseon Cave in Gangwon-do. It is in Samchok. I am interested in going there.