Nam Hong-Joo (Bae Suzy) comes here in episode 13 of While You Were Sleeping (2017) (당신이 잠든 사이에) (SBS, 2017) blaming herself for what has happened to Han Woo-Tak (Jung Hae-In). While crying, she stumbles into Jung Jae-Chan (Lee Jong-Suk) who had dreamed about this situations and came here armed with a box of tissues. From afar — as we learn in episode 14 — Woo-Tak observes all this.
Sangdong Lake Park [상동호수공원] is located in Bucheon City [부천시], a city located between Seoul and Incheon. It is known for its wild poppy fields (which you also see in While You Were Sleeping (2017))
Address: 경기 부천시 길주로 16
549 Sang-dong, Wonmi-gu, Bucheon, Gyeonggi-do, South Korea
Geolocation: 37.505021, 126.744296
To get here: Samsan Gymnasium Station [삼산체육관역], Line 7, Exit 1
— submitted by Monica