The accident, which occurred at a resort in Russia's North Caucasus Mountains, claimed the life of extreme sport enthusiast D. Burakov who suffered a broken neck in the fall, the official Russian news agency RIA Novosti reported.
Vladimir Shcherbov, 33, was hospitalized with a concussion and multiple lacerations to his head and body, the Investigative Committee said in a statement.
The two were participating in a sport known as zorbing that originated in New Zealand.
The ball they were riding in was supposed to come to a gentle stop at the bottom of the mountain but instead veered off course and plunged down a ravine.
Russian officials have opened a criminal negligence investigation into the deaths.