Looking down from nearly 1,000 feet above the ground is already a terrifying experience -- now imagine Spencer Seabrooke's view from the middle of a loose rope. The slackliner broke a world record by walking 64 meters (210 feet) on a slackline mounted 290 meters (951 feet) above the ground, without being attached to the line.

Rigging a rope across the Chief North Gully in Squamish, British Columbia, and crossing that long gulf would be a daunting task for even the most accomplished slackliner. The sport is similar to tightrope walking, except the webbing is not as taut. That allows for a bit more, well, slack and a bit more bounce depending on the individual's preference. Highlining is the more extreme version of the sport, in which the line is rigged very high off the ground. Usually these slackliners are attached to the line and there are a lot of safety measures in place.

Some slackliners like Seabrooke and Dean Potter -- who slacklined across China's Enshi Grand Canyon in 2012 -- like a little more danger and take part in free solo slacklining. That's highlining without being attached to the line. For the world record, Seabrooke and his team set up a highline at the Chief North Gully on Aug. 2.

The video shows the dizzying heights of Seabrooke's attempt and in the first 30 seconds there's a terrifying slip. Seabrooke quickly recovers, but it's definitely a nerve-wracking moment.