This was the said tunnel featured in Tunnel (터널) (OCN, 2017) that started 80s detective Park Gwang-ho’s (Choi Jin-hyuk) time-travelling ordeal to the present day.
Gujinpo Tunnel [구진포폐터널] is an abandoned tunnel that runs today in parallel to Gujinpo-ro [구진포로] in the village of Gaun [Gaun-ri/가운리] in Naju’s Dasi Township [Dasi-myeon/다시면].
Anchang-dong, Naju-si, Jeollanam-do
전남 나주시 안창동
West entry: 35.004003, 126.675580 (towards the woods)
East entry: 35.004508, 126.677621 (towards the main road)
— submitted by Mich KDL