Visitors party during the summer carnival in a water park in Taizhou, Jiangsu province. [Photo provided to China Daily]

It also has branches in Shanghai, Guangdong province's Shenzhen, Sichuan province's capital, Chengdu, Hubei province's capital, Wuhan, and Tianjin.

The chain has received more than 100 million visits.

Adults aged 20-35 are the main demographic, deputy general manager Li Xiangyang says.

Beijinger Zhang Guangqi believes it's "more thrilling" than Hong Kong's Disneyland and Los Angeles' Universal Studios.

The 33-year-old says the foreign parks are perhaps a better fit for parents bringing children.

Visits peak in July and August because of summer vacation. Up to 10,000 people visit during workdays and up to 20,000 arrive on weekend days, Li says.

Li believes foreign brands bring not only competition but also opportunity.

Disneyland focuses on its animated fairy tales and Universal Studios adopts movie themes, while Happy Valley focuses on the simple joys of thrills.

Shenzhen's Happy Valley grew by more than 20 percent when Hong Kong's Disneyland opened 45 kilometers away in 2005. The distance is comparable to that of both parks in Shanghai.

"Foreign theme parks introduce Western elements," Li says.

"This entices domestic parks to differentiate themselves by developing more Chinese experiences."