Zhang Dewu swims in the Songhua River in Harbin, Heilongjiang province, as temperatures dropped below -10 C recently. [Photo by Zhang Qingyun/for chinadaily.com.cn]

Zhang Dewu swims in the Songhua River in Harbin, Heilongjiang province, as temperatures dropped below -10 C recently. [Photo by Zhang Qingyun/for chinadaily.com.cn]

Before diving into the icy river, Zhang Dewu does some warm-up exercises, including dousing his body with room-temperature water. [Photo by Zhang Qingyun/for chinadaily.com.cn]

Zhang Dewu swims in the Songhua River in Harbin, Heilongjiang province, as temperatures dropped below -10 C recently. [Photo by Zhang Qingyun/for chinadaily.com.cn]