Hot-air balloons fly over the city zone during the 7th Hot Air Balloon Festival and 2013 H1 China Hot Air Balloon Challenge in Haikou, capital of South China's Hainan province, June 18, 2013. A total of 15 hot-air balloons participated in the event Tuesday to fly across the Qiongzhou Strait from the city of Haikou and reach a designated place in neighboring Guangdong province. [Photo/Xinhua]

Hot-air balloons fly over the Millenium Bridge during the 7th Hot Air Balloon Festival and 2013 H1 China Hot Air Balloon Challenge in Haikou, capital of South China's Hainan province, June 18, 2013. [Photo/Xinhua]