People watch jellyfishes at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)

A staff member checks temperature of visitors at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)

A tourist watches white whales performance at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)

Children watch a white whale at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)

Visitors watch fishes at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)

People watch penguins at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)

Visitors watch a sea lion perform at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)

A visitor waves to a white whale at Polarland in Harbin, capital of northeast China's Heilongjiang Province, March 23, 2020. Polarland in Harbin reopened on Monday, and the number of visitors are limited to no more than 400 per day. (Xinhua/Wang Jianwei)