The 2021 China Mountain Marathon Series (Jilin Changbai Mountains Division) opens in Changbai Mountain Scenic Area in Northeast China's Jilin province on April 18. The marathon event, with 3,000 participants, has three categories: 42-kilometer individual race, 21-km individual race, and 9-km fitness run. The race track requires participants to run along tarmac, gravel, ice and snow. [Photo/people.com.cn]

A mountain marathon kicks off in Changbai Mountain Scenic Area in Jilin province, April 18. [Photo/people.com.cn]

A marathon runner is photographed during the event, April 18. [Photo/people.com.cn]

A marathon runner crosses the finish line, April 18. [Photo/people.com.cn]