In search of the ultimate roller coaster thrill
22 October 2013 Last updated at 23:52 BST
Technology has transformed the theme park thrill ride, fuelling a global race to create the fastest, tallest, scariest rides the world has ever known.
But are we reaching the limits of what the human body - and theme park budgets - can stand? What will the thrill ride of the future look like?
The BBC's Richard Taylor visited Six Flags Adventure Kingdom near San Francisco, California, to try out some of the rides and speak to those in the know.
And if you want to know more about thrill ride technology, click here for our accompanying feature.