A patrol boat is on duty on the sea covered by floating ice near Qinhuangdao, north China's Hebei Province, Jan. 24, 2013. The floating ice in Bohai Sea has expanded due to the cold snap. (Xinhua/Yang Shiyao)

A patrol boat is on duty on the sea covered by floating ice near Qinhuangdao, north China's Hebei Province, Jan. 24, 2013. The floating ice in Bohai Sea has expanded due to the cold snap. (Xinhua/Yang Shiyao)

A fishing boat is stranded in the sea ice in Qinhuangdao, north China's Hebei Province, Jan. 24, 2013. The floating ice in Bohai Sea has expanded due to the cold snap. (Xinhua/Yang Shiyao)

Photo taken on Jan. 24, 2013 shows the sea covered by floating ice near Qinhuangdao, north China's Hebei Province. The floating ice in Bohai Sea has expanded due to the cold snap. (Xinhua/Yang Shiyao)

A vessel sails on the sea covered by floating ice near Qinhuangdao, north China's Hebei Province, Jan. 24, 2013. The floating ice in Bohai Sea has expanded due to the cold snap. (Xinhua/Yang Shiyao)