And the accident has led to calls from "the New Zealand inventors of zorbing ... for a global code of safe operations to try and stamp out cowboy operators," the Otago Daily Times reports.

The transparent plastic ball—called a zorb—veered off course and sailed over a precipice in the rugged Caucasus Mountains of southern Russia. One man died and the other was badly injured.

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 ...