This is a very fun traverse of the southern part of Bukhansan National Park (the Baegundae area). This route hits 15 major and minor peaks along the way, has a baseline difficulty of about a class II scramble for short sections, with route variations posted on signs showing alternative sections you can use to add sections up to 5.8 YDS if you want. So fun.
The map GPS track is somewhat an underestimation. My actual watch gave me 13.6 miles and 4,350 ft of elevation gain with all the switchbacks and up/downs.
Restaurants and cafes exist at both trailheads.
Would be a really great training run, but I'd suggest going in the early morning during the work week. Koreans like to hike very socially and in large numbers. I tried to run as much as I could, but I spent a ton of time having to walk slowly behind large crowds because I was there on a beautiful fall Saturday.
Start by getting off at Bulgwang Station. From there, it's about a 15-minute walk north to the trailhead tucked up an alley between high-rise apartment buildings. From there, it is relatively easy. Stay on the high ridgeline trail all the way until you summit at Bukhansan's highest peak, Baegundae. Then head downhill to the east on the significant main train until you get to the trailhead.
The trails are well marked in Korea, you can look at the peak names on Kakao Maps, and the trail signs point to the next peak at key junctions. Just keep going peak to peak.
The main challenges here are rocks. Much of the trail is on slab granite, not necessarily steep, but it feels like you are never standing on flat ground, so it's hard on the calves and ankles. There are sections with stairs, sections with hand ropes and rails, etc to help with the steepness.The stairs are unavoidable, but you can choose not to touch any handrails or ropes, and it makes some sections fun, slabby scrambles, maybe class III in some short sections.
Right by the Munsubong area is my favorite spot, where it gets really steep on slab granite, and there is a very airy step, protected by hand rails. If you don't touch any handrails, it's definitely exciting for a typical runner. Rock climbers will be amused but not terribly impressed, however it's a really fun run.
You can't possibly get lost in this park. If you are ever in doubt, walk downhill on any trail and you'll end up back in the wonderful mega city of Seoul or use the Trail Run Project mobile app
Amazing views of the city on this trail, don't miss it! Fall colors also abound, it's beautiful on a clear fall day.
Local hiking clubs would suggest this as a 7-10 hour run, fast people will be able to do it in about 4.