Hainan (海南) is an island province at the southernmost part of China, just across the Gulf of Tonkin from Vietnam. "Hainan" literally means "South of the Ocean At one point, Hainan was considered a backward place serving as a place of exile for failed officials.Hainan is China's smallest province, and also the largest island under the jurisdiction of the People's Republic of China. Hainan is also the only island province administered by the PRC..