I spent my first night in Seoul at the Yeouido Park cherry blossom festival. Took a long train journey to Yeouinaru Station (subway line 5) and exited from either exit 1 or 2.
Official website: http://english.visitseoul.net/event-festival/Yeongdeungpo-Yeouido-Spring-Flower-Festival-2016_/16479
I can’t remember which exit I took but I do remember buying 11 pairs of socks from the bustling train station. There were a lot of stores in the underground station! The store had a “Buy 10 + 1” sale and each pair ended up costing less than 1000Won! Aren’t they adorable 8D??