我国唯一一座什么都免费城市，人口2300设8座机场，外国人不能进

Core Viewpoint - Sansha City, a unique Chinese city with a permanent population of less than 2,500, boasts eight airports and offers free healthcare, education, and housing, while prohibiting foreign access, highlighting its strategic importance in the South China Sea [1][3][4]. Group 1: Strategic Importance - Sansha governs over 2 million square kilometers of maritime territory, equivalent to one-fourth of China's land area, emphasizing its significant strategic value [3]. - The South China Sea is rich in resources, with 70% of China's proven oil reserves and 30% of natural gas reserves located here, alongside an annual fishery output value exceeding 1 billion [4]. - Control over this maritime area is crucial for international shipping routes, with tens of thousands of vessels passing through annually, making it vital for the Asia-Pacific economy [4][5]. Group 2: Infrastructure and Living Conditions - Sansha has constructed eight airports on small islands, with Yongxing Island capable of accommodating large transport aircraft, serving both civilian and military purposes [5]. - Residents enjoy a range of benefits, including free medical care, education, and government-supplied groceries, reflecting the government's commitment to ensuring their well-being [3][4]. Group 3: Environmental and Operational Challenges - The city faces challenges such as reliance on seawater desalination for freshwater and vulnerability to typhoons, which can disrupt water supply [9]. - The harsh environment leads to rapid corrosion of materials, necessitating innovative solutions like solar power and waste management systems to maintain sustainability [9]. Group 4: Governance and National Sovereignty - Sansha represents a modern model of border governance, maintaining territorial integrity and national interests despite external pressures [10]. - The integration of military and civilian efforts, such as fishermen collecting hydrological data, underscores the importance of security and sovereignty in the region [7][10].