In Seoul, there are several big park & forest, we call it, Seoul Sup.
One of them is Buk Seoul Sup. It is located in Gang-buk area.
In the park there are a exhibition hall, an arts center, cafes and restaurants. You can see many family, friends, and couples to enjoy picnic. I love to go there in spring to see flower blooming. I used to date with my husband or drink beer with my friend on the grass. I recommend you to go there in spring or fall, bringing with a picnic mat.
108 Beon 3(sam)-dong, Gangbuk-gu, Seoul, South Korea