At 637 meters above sea level, Mount Pukhan may not very high or overly difficult, but it is visited and climbed by thousands of mountain loving Koreans every year and offers spectacular views of granite cliffs and green valleys from its summit.
While it only takes a few hours to climb -- those hours will be well spent. It's amazing that in the middle of seoul (a bustling city of 14mio) one can take a 20 minute subway ride and, aside from the hundred of people on the mountain with you, get away from it all.
Essentially the park consists of many many peaks of granite ranging in height from 836 for Baegundae, Nojeokbong (716m), Insubong (810m), and Mangyeongdae (799). They're all connected so once you've climbed up one you can attempt the next. Scattered throughout the park you can try your hand at other ranging from 675m to 7540m.
These granite rocks offer options for everyone from the contemporary climber after a 50ft pitch at 800ft to a simple stair walk-up.
The mountain itself is easy enough to reach as it's in the North West section of Seoul easily accessible by subway, bus, or taxi.
The easiest method is to take the orange #3 line to the stop called Gupabal. The appropriate exit is clearly marked in the subway, but once you've exited you'll either need to take a mini-bus to the entrance or a 5-minute taxi. The bus number from Gupabal Station to Pukhansan is 156.
It should be farely obvious where to go as there will likely be 20 people getting off the subway at the same time all dressed to the nines in their hiking gear.
A very helpful subway map.
No permit is required, but there is a 1600 Won (around US$1.50) entrance fee required for entry. Hand them the money, take the ticket, and start walking.
When To Climb
In theory you can climb this mountain anytime (and people definitely do), but I recommend you climb on a weekday as it can get incredibly crowded (think Mt. Fuji). I also suggest the autumn when temperatures are neither too hot or too cold and the surrounding countryside will be alive with colour. The granite can get rather slippery in the rain so I personally suggest you do this hike on a dry day.
For a fee of 3000W (US$2.80) you can pitch a tent in the park, but, as far as I know, most people just visit the park for the day. There is also Tobong Mountain House with hostel style rooms available for another 3000W a night .
In theory you can climb this mountain anytime (and people definitely do), but I recommend you climb on a weekday as it can get incredibly crowded (think Mt. Fuji). I also suggest the autumn when temperatures are neither too hot nor too cold and the surrounding countryside will be alive with colour.