An international expo at a glittering hi-tech venue was flagged off by South Korea's President with a huge seafront display of fireworks and lasers.
After four years of preparation and $10 billion investment, a 2,000-strong crowd -- including foreign delegates -- cheered as the sky lit up above the southern city of Yeosu.
A total of 104 nations and 10 international organisations will stage exhibitions over the next three months at the expo which has the theme "The Living Ocean and Coast".
President Lee Myung-Bak opened the expo, hailing its focus on "the beautiful coexistence of the ocean and humankind."
The "Big-O," a 48-metre (158-foot-tall) round steel structure and the centrepiece of the site, displayed colourful hologram images.
Dozens of fountains shot colourful water jets as performers danced and sang and an orchestra played music on a floating stage.
The 25-hectare (60-acre) area -- a former cement terminal now turned into a site housing pavilions and a giant aquarium -- opens to the public on Saturday.
Organisers hope for about 10 million visitors, including up to 800,000 foreigners mainly from China and Japan, to the small city of 300,000 people long known for a scenic coastline and hundreds of nearby islands.
A new ferry terminal capable of handling six cruise ships stands right by the exhibition site to accommodate tourist arrivals.
Organisers predict the event will create some 80,000 jobs and bring economic benefits worth 19 trillion won ($17 billion) -- outweighing the massive spending on the site.
Expo 2012 Yeosu is being held between the headline World Expos, which are staged every five years. The last was in Shanghai in 2010.