Zorbing - effectively throwing yourself down a slope in a giant ball - has become the latest extreme sport craze to sweep the world.
The zorb protects the user with a cushion of air
Although zorbing was invented in 2000, it has only recently begun to take off around the world.
It involves a giant plastic ball, which has two skins - one inside the other. The person zorbing is in the area between the skins, which is pumped up with air. The middle ball effectively suspends them on a cushion of air 700mm off the ground, and the ball is then rolled down a hill.
"It's not really amazingly scary, it's not an amazing adrenaline rush - it's just bizarrely fun," the inventor of zorbing, Andrew Akers, told BBC World Service's Culture Shock programme. "I don't know why."
Like a number of other extreme sports, such as bungee jumping, zorbing originated in New Zealand.
Mr Akers explained that there are a number of reasons New Zealanders why have developed an attraction to developing these types of activities.
"We're so far away from anywhere that we've really had to make our own fun," he said.
"Also, if you injure yourself, then the government is going to pay for you to not only get back on your feet, but they're going to rehabilitate you and get you back into the workplace as well.
"This means that we have a non-litigious society, and so a lot of things start up that possibly would not be able to start up anywhere else in the world."
There are two different ways to zorb - either harnessed inside the ball, or "hydrozorbing", which involves putting water in the ball, which zorbers can slide around on as it revolves.
Mr Akers explained that initially, there were fears that people would be sick. "You can imagine if it happened it would be completely disgusting," he said.
"However, of over 100,000 people who have now done it, no-one has ever thrown up inside the zorb."
This is because as the zorb is 3.2m in diameter, it rotates only once every 10m - so even down 100m of hill, it will make a full rotation only 10 times.
"The whole feeling is actually not that quick - it's kind of a slow going over and over," Mr Akers said.
"For some people this will be the scariest thing they do, but for people who do bungee jumping or skydiving or white water rafting, this really is nowhere near that sort of level of adrenaline or fear factor," Mr Akers added.