A fun feature of the Yeosu Expo is the Passport Stamp Trail

Each venue has a self stamping area where you can fill in another stamp from a place you have visited

Unfortunately I'm told you have to buy the passport and I never saw where. It would be a good idea to hand them out free with the ticket to encourage people to visit more areas they may not have been aware of. 

The ticket price, travel cost, food and accomodation are enough expenses for the weekend without adding another novelty to the list