Hainan
Chinese island province in the South China Sea and home of a major naval base
Hainan is China's island province in the South China Sea, home to the Yulin naval base at Sanya. Naval News said on 15 September 2026 that China has tested 35m and 45m uncrewed submarines off its coast.
Last refreshed: 7 October 2026
Timeline for Hainan
Mentioned in: China may build a drone-sub mothership
Autonomous Systems: Land & SeaBackground
Hainan's waters are where China tests its largest robot submarines. Naval News said on 15 September 2026 that China has tested two very large uncrewed submarines, of 35m and 45m, off the island, and assessed that a hull building at Hudong-Zhonghua in Shanghai is the first mothership for such vehicles. Satellite imagery published in 2022 first showed two extra-large uncrewed submarines in floating docks at Gangmen Harbour, west of the main naval base at Sanya.
Hainan became a province separate from Guangdong in 1988. Its capital is Haikou, and it had about 10.1 million residents in 2020. The Yulin naval base at Sanya on the south coast is the PLA Navy's traditional base in the South China Sea, with nuclear submarines and aircraft carriers berthed at Longpo on Yalong Bay.
The province administers China's claims to the Paracel and Spratly Islands through Sansha city, which puts its government at the centre of the South China Sea disputes. On 1 April 2001 a US Navy EP-3E surveillance aircraft collided with a Chinese J-8II fighter and landed at Lingshui on Hainan; the Chinese pilot was killed and the US CREW were held for 10 days.