Longpo Naval Base (East Yulin Naval Base)

Longpo Naval Base, also referred to as East Yulin Naval Base, is a People's Liberation Army Navy installation for nuclear-powered submarines on the southern coast of Hainan Island, China. It lies on Yalong Bay near Sanya, adjacent to the older Yulin Naval Base, and is the point of Chinese territory closest to the edge of the continental shelf, roughly 50 nautical miles (93 km) from the 200-metre isobath. The Paracel Islands and Da Nang, Vietnam, lie about 150 nautical miles (280 km) away.

The base supports nuclear-powered ballistic missile submarines, including the Type 094, each armed with JL-2 submarine-launched intercontinental ballistic missiles. A Shang-class (Type 093) attack submarine was observed entering the underground facility in August 2020 in imagery from Planet Labs. Berthing at the base is sized for aircraft carriers, and the pier arrangement, which includes two piers of about 950 metres, is assessed as sufficient for two carrier strike groups or amphibious assault ships.

The distinguishing feature of the installation is an underground complex excavated into the coastal terrain, with caverns assessed from reconnaissance satellite imagery as able to shelter up to about twenty nuclear submarines. Tunnel entrances give submerged or covered access from the harbour, allowing boats to enter and leave without being observed from above. Surface facilities comprise the piered harbour on Yalong Bay.

The site has been in naval use since 1955 as part of the Yulin base area serving the South Sea Fleet. Imagery published by the Federation of American Scientists in February 2008 documented construction of the large-scale underground submarine facility, and the base has subsequently been identified in reporting by several intelligence services as the principal southern basing point for China's ballistic missile submarine force.