South Korean islands that are located in the Yellow Sea include Anmado, Baengnyeongdo, Deokjeokdo, Daebudo, Ganghwado, Gageodo, Heuksando, Jejudo, Silmido, Yeongjongdo, among others.
There are also seas where you can swim in there aside from Jeju?
I had students before and they said the beaches in the east side is good for swimming than in the west.