While on a two week business trip to Seoul, South Korea, I had the opportunity to summit the highest peak in nearby Mt Puk'an-Sansong National Park. Not having known in advance that there were any peaks to climb I had not brought any cold weather gear with me. So on a bright sunny cold (18 degrees) Saturday morning I hopped the local subway and began to make my way across town attired in running shoes, every t-shirt I had brought on the trip, my softsided briefcase (to carry food and water) and my trench coat. After climbing out of the subway near the Sejong Cultural Center I took bus #6 for about 45 minutes out of the heart of the city to the edge of the foothills at the terminus of the line in Uidong.
The terminus for the bus is a few km from the Toson-sa Temple. At this point you can wait for the bus that runs to the temple or walk up. The walk takes about 30 minutes, initially through a group of shops specializing in hiking supplies. There are also a few small restaurant that sell takeaway snacks like fried chicken legs and tempura vegetables. The bus takes around 10 minutes and costs W100 (approximately 800 Won to the dollar). Put your money into the donation box next to the temple when you disembark from the bus.
The terminus for the temple is in a small plaza with a Buddha statue in the center. To the left if this is the entrance to Tosan-sa Temple, and directly ahead is an entrance to the national park. Don't take this entrance. Instead, go into the temple grounds, and have a look around the temple. The multi-building complex is very impressive with many rooms in which people perform prayers and the monks(?) who live there go about their business. I went inside several of the buildings to try to build up a little warmth. This proved fruitless though, since one must remove one's shoes before entering the buildings. Upon exiting the buildings one loses all newly acquired warmth through the tedious process of re-finding one's shoes in the stack, as one stands in one's socks in the snow and ice.
Within the temple grounds, to the left and below the main temple complex, is another entrance to the national park (about W400). You can begin your climb here. (You will not be issued a map, and I do not know if any are available. I climbed without one.)
The hiking trails are for the most part fairly clear, and there's no real danger of becoming TLI (Temporarily Locationally Impaired). In my particular case a few days earlier there had been the single day largest snowstorm in Seoul in five years and the resulting dump covered most of the trails. But, since many people had climbed up before me that day the path was manifest. The main thing is to keep bearing right. Within about 30 minutes you should reach the fortifications and the Dragon's Cliff Gate. At this point continue bearing right and climbing upwards until you reach a fork in the path which gives you a choice of ascending either of the two peaks. The path to the right leads to Paegun-dae (the highest peak in the park) and is the best option - it has steel cables embedded in the mountain (ala many European trails).
These cables were the only thing that enabled me to summit. For the last 800 feet or so the climb is mostly on bare rock and this happened to be covered by various and sundry sheets of ice. Most everyone summitting that day had at least instep crampons on their boots. Many people descending took one look at me in my sneakers and tried their best to convey the sense of danger.
The last ascent to the summit of Paegun-dae is a reasonably stiff climb, and I had to pull myself up hand over hand on the steel cable (alas I had not brought gloves with me, so my palms suffered somewhat during these 30 minutes). Just before reaching the summit two girls came around the corner on their descent and broke out in gales of laughter, pointing at me in my trenchcoat and briefcase and saying, "You English?" I nodded yes and they took their picture standing next to the ridiculous American before continuing their descent still giggling.
The views from the summit are quite impressive: both of the sprawl of Seoul and of the outlying mountainous countryside. I asked a couple of teenage boys to take my hero shot and they invited me to descend with them. One of the other summiteers took pity on me and gave me his glove liners to wear on the way down (the thermometer read six below zero on the summit, but that included wind chill effects). The two boys took great delight in trying out their English with such phrases as, "Do you know Air Jordan?" and "Do you like Sylvester Stallone? He very bad boys." During the hour long skating, sliding, boot skiing descent I was queried as to my personal knowledge of just about every major NBA player as well as many Hollywood stars.
For the descent, bear left at the bottom of the rocky summit and go under an old gate. This path heads straight down to Toson-sa Temple. Or as an alternative, turn left at the summit fortification and descend past a hiker's hut and small camping village before making a right at a fork and climbing back over a small ridge to the entrance to the national park (at the Buddha statue).
In either event there is plenty of food and water (and videotapes of the temple) at the base parking lot.
There are many other hiking trails within the park as well as at least 20 summitable peaks (including several that are class 5). I would rate this peak a class 2 in summer, and class 3 in winter.
(This review borrows heavily from the "Lonely Planet Guide to Seoul")