Yanghwa Hangang Park
When I was studying in Korea, I loved finding a spot to relax by the river, and Yanghwa Hangang Park is another park located along the Han River. It's less crowded than Yeouido Park. Personally, I find this park more serene, with more trees and shade. It's a great place for a picnic, and there's a convenience store nearby, though you might want to bring your own food. The park is also in the city, about a 15-minute walk from Hongdae.