From BBC News:

NZ’s extreme ball sport takes off

Zorbing - effectively throwing yourself down a slope in a giant ball - has become the latest extreme sport craze to sweep the world.

Although zorbing was invented in 2000, it has only recently begun to take off around the world.

(more here)

I’ve seen these “Zorb” balls at Burning Man,  although until now I didn’t realize they were called Zorb Balls.