If there’s anyone of you wanting to book some cheap flights from Seoul to Jeju Island, you can do so on:
- Jeju Air – www.jejuair.net
- Hansung Airlines – www.gohansung.com
Note that both websites are in Korean and I am unable to find any English translations. Also note that both airlines flies from Gimpo Airport to Jeju International. Only Hansung flies from Cheongju Airport to Jeju International.
To get from Incheon Airport to Gimpo Airport, you have a choice of bus or train. Both takes about the same time (40 mins) unless the traffic slows the bus down.
Good luck in your quest. I’m taking out my Korean dictionary