An underwater performance is staged at Harbin Polarland in Harbin, northeast China's Heilongjiang Province, Sept. 25, 2020. The ocean-themed park has introduced a series of new shows ahead of the Mid-Autumn Festival holidays. (Photo by Zhang Tao/Xinhua)

Visitors watch an underwater performance at Harbin Polarland in Harbin, northeast China's Heilongjiang Province, Sept. 25, 2020. The ocean-themed park has introduced a series of new shows ahead of the Mid-Autumn Festival holidays. (Photo by Zhang Tao/Xinhua)

A trainer and a Beluga whale stage an underwater performance at Harbin Polarland in Harbin, northeast China's Heilongjiang Province, Sept. 25, 2020. The ocean-themed park has introduced a series of new shows ahead of the Mid-Autumn Festival holidays. (Photo by Zhang Tao/Xinhua)

An underwater performance is staged at Harbin Polarland in Harbin, northeast China's Heilongjiang Province, Sept. 25, 2020. The ocean-themed park has introduced a series of new shows ahead of the Mid-Autumn Festival holidays. (Photo by Zhang Tao/Xinhua)

Visitors watch an underwater performance at Harbin Polarland in Harbin, northeast China's Heilongjiang Province, Sept. 25, 2020. The ocean-themed park has introduced a series of new shows ahead of the Mid-Autumn Festival holidays. (Photo by Zhang Tao/Xinhua)

A trainer and a Beluga whale stage an underwater performance at Harbin Polarland in Harbin, northeast China's Heilongjiang Province, Sept. 25, 2020. The ocean-themed park has introduced a series of new shows ahead of the Mid-Autumn Festival holidays. (Photo by Zhang Tao/Xinhua)