The most convenient way to get to U-do island is via passenger ferry. Make your way to Seongsan on the east coast of Jeju-do and purchase a ticket at the port terminal. There are various companies offering services ranging from fishing charters to sailing cruises. You must head toward the ferry passenger services desk and purchase a round trip ticket. Ferries takes 15 minutes to and from and typically leave once an hour on the following seasonal schedules:
Winter (Oct.-Mar.): from Seongsan 08:30-17:00 / from U-do 08:00-16:30
Summer (Apr.-Sep.): from Seongsan 08:00-18:30 / from U-do 07:30-18:00
If driving from Jeju, you may take your vehicle on board but additional fees do apply.