Paramedics scrambled to Matt Johnson's side after the illusionist failed to free his head from chained glass box full of water after nearly two minutes.
For the semi-final of the competition, Johnson was put in a padlocked straightjacket and then locked into handcuffs.
But Johnson became visibly more panicked as he could not get out by what he called the "safe" time of 1 minute, 45 seconds.
Paramedics didn't end up having to intervene as Johnson managed to free himself - and just in the nick of time, it would seem - as he spluttered for air.
