A boat is trapped by sea ice in Qinhuangdao, north China's Hebei Province, Jan. 23, 2016. Sea ice along Bohai Sea and northern Huanghai Sea continued to expand due to a strong cold front. The North China Sea Marine Forecasting Center of State Oceanic Administration issued a blue alert for sea ice in Liaodong Gulf for three consecutive days since Jan. 21. (Xinhua/Yang Shiyao)