The Big-O was constructed to connect the breakwater with the Expo site. Many important events will be held at the Big-O, deemed as the heart of Yeosu Expo. The Big-O, a gigantic structure resembling the letter O produces special effects with water jets and a stage that goes up and down freely. It is 120 meters wide and consists of three fan shaped structures in a row. It has 345 fountain nozzles in total which shoot water going as high as 70 meters. The Big-O also presents a mix of laser show, holograms and a water fountain show. The fountain show will be presented every hour on weekdays. The Big-O is a perfect place to visit with family for it is an open area and you can feel the nature while watching the show

During the entire period of Yeosu Expo, you will be able to see huge LED screens hanging from the ceiling. The screen is 218 meters wide and 30 meters long which is 6,324 units of 60 inches TVs combined altogether. The large screen installed on the ceiling of the passageway of the International Pavilion displays various forms of marine life as well as Korean traditional folklores such as “The Life of Shim-Cheong,” and “The Four Guardian Gods of the King” along with children's paintings of Korea, China and Japan that represent the theme of the Expo. Unlike other pavilions, visitors don’t have to wait in a long line to watch the EDG, but simply look up and see the screen while walking. Visitors can go interactive at the EDG by using their smartphones to send their pictures with a message to be shown up on the LED screen.

The Sky Tower is a symbolic construction made by transforming a pair of industrialization-period abandoned silos into a beautiful artistic masterpiece. On the outside of the Sky Tower installed is a pipe organ named ‘Vox Maris’ (meaning ‘the sound of the sea’ in Latin) which makes the greatest sound in the world. The pipe organ, based on the Expo’s marine concept, was created after a boat horn (referred to the sound of the sea). It has 80 scales similar to a piano and the maximum sound of 138.4 decibels so it delivers its sound as far as 6 kilometers away. The silo No. 1 has a theater showing a film of wonderful scenery of the south coast. The silo No. 2 houses a facility that holds 12 tons of desalinated seawater prepared for you to try. On the observation deck, you can watch the entire Expo site, downtown Yeosu and even Odong Island at one sight.

It is the biggest aquarium in Korea, where you can observe 34,000 marine animals from 281 species including rare species such as Baikal seal and Russian beluga. The Aquarium consists of a 360 degree 'Aquadome' and a large-sized water tank, in which about 20,000 sardines move around. The Aquarium also has a 3-D theater, equipped with 41 separately operated seats, that displays a thrilling 3-D animation of small fishes’ running away from a shark. The animation lasts for about 5 minutes. The Aquarium is free of charge but the 3-D theater charges 5,500 Korean wons for adults and 4,500 wons for students under 18.