SEOUL, South Korea -- They came from all over the world, poles in hand, and feet ready to inch more than half a mile across a high wire strung over the Han River in a spine-tingling battle of balance, speed and high anxiety.

As part of its annual city festival, the South Korean capital staged Thursday what was billed as the world's first high-wire championship, drawing 18 contestants from nine countries for three days of supreme feats of concentration.

Each acrobat must navigate the 1.2-inch-thick wire that spans the river, with the top prize of $15,000 going to the person crossing it fastest.

The contestants _ 14 men and four women _ include such masters of the high wire as Jade Kindar-Martin of Shelburne, Vt., a former Cirque du Soleil performer who once crossed London's River Thames at a height of 150 feet, and Colombia's Alan Martinez, who ambled across the Amazon.

They will face Adili Wuxiuer of China _ the world record-holder for distance who walked on a wire nearly a half-mile across the Chongqing Cliff at a height of 2,250 feet in 2003.

Organizers in Seoul said stringing the wire across the Han made it the longest-ever such high wire, meaning anyone making it across will break the record for distance.

The iron cable was supported by 72-foot-high towers on either bank of the river. A safety net was deployed under the sections of the wire over the riverbanks; otherwise the walkers faced a plunge into the swirling gray water.

Alexey Marchenko of Russia was one of two competitors who lost his balance and fell into the river Thursday with only 164 feet to go. Some in the crowd screamed as he splashed loudly into the Han, followed about a second later by his pole.

Damp and disqualified, Marchenko appeared unhurt as he chatted with rescuers in a motor boat that had scooped him from the water. All the contestants wore life vests.

The main wire _ with yellow flags every 82 feet _ was supported by stabilizing lines to keep it from swaying sideways, but it sagged under its weight across the middle of the river, meaning the drop to the water was actually much lower.

Thursday's first competitor _ Kwon Won-tae of South Korea _ glided across the wire to the cheers and applause of hundreds of people on each bank of the river that bisects Seoul.

Kwon, a famous tightrope walker in South Korea, flinched when his balance was disrupted by the wind and birds before completing the walk in 17 minutes and 7 seconds.