I wanted to climb Beihan Mountain when visiting Seoul. It was a bit confusing to get there but basically just follow the hikers. I wasn’t a very robust person, so when I said climbing was difficult, it was really difficult. I spent 5 hours climbing up and down, including rest. It was well worth climbing up the top. I visited in autumn so the park was beautiful and the weather was nice and cool. Make sure you have plenty of water and snacks. It was a full day of activity.