Overview: The World's Most Contested and Valuable Sea
The South China Sea is a marginal sea of the Pacific Ocean, covering approximately 3.5 million square kilometers. It is one of the most strategically and economically vital bodies of water on Earth, with an estimated $3.4 trillion in trade passing through it annually — roughly one-third of global maritime commerce.
Global Commerce Artery: Nearly all trade between East Asia and the rest of the world passes through the South China Sea — including exports from China, Japan, South Korea, and Taiwan, as well as energy imports flowing from the Persian Gulf through the Strait of Malacca. Any significant disruption would cause immediate and severe global economic consequences.
The South China Sea is also one of the most geopolitically contested regions in the world. China claims the vast majority of the sea under the controversial "nine-dash line," overlapping with the exclusive economic zones of Vietnam, the Philippines, Malaysia, Brunei, and Indonesia. Military tensions, artificial island-building, and naval confrontations make it one of the world's most closely watched maritime flashpoints.
Geographic Extent
- North: Taiwan Strait; southern China coast
- West: Vietnam, Malay Peninsula
- South: Strait of Malacca, Indonesian archipelago
- East: Philippines, Luzon Strait
- Key passage: Strait of Malacca (SW); Luzon Strait (NE); Taiwan Strait (N)
- Length: ~3,500 km (north–south)
Island Groups & Disputed Features
- Spratly Islands: ~750 reefs, atolls, cays — claimed by 6 parties
- Paracel Islands: Occupied by China since 1974; claimed by Vietnam
- Pratas Islands: Controlled by Taiwan
- Macclesfield Bank: Submerged; claimed by China and Taiwan
- Scarborough Shoal: De facto Chinese control since 2012; claimed by Philippines
Philippine Sea Deepest Point
- Maximum depth in SCS: 5,559 meters (West Luzon Basin)
- South China Sea is deep in the central basin but shallow on continental shelves
- Average depth: ~1,212 meters
Strategic Importance: Asia's Trade Superhighway
The South China Sea connects the Indian Ocean to the Pacific, making it the world's most commercially intensive sea lane and a critical node in Asia's manufacturing-led global economy.
Strait of Malacca
World's most important shipping chokepoint
- Only 2.7 km wide at its narrowest point (Phillips Channel)
- 90,000+ vessels transit annually
- Handles ~25% of all traded goods globally by some estimates
- ~16 million barrels of oil per day (second only to Hormuz)
- Connects Indian Ocean to South China Sea
- Piracy has historically been a concern; now significantly reduced
Major Shipping Lanes
Asia–Europe via Indian Ocean (via Malacca)
- China/Japan/Korea → Malacca → Indian Ocean → Suez → Europe
- World's highest-volume container trade route
- Monthly capacity: billions of dollars in electronics, textiles, machinery
Trans-Pacific (via Luzon/Taiwan Strait)
- Asia → Pacific → North America
- South China Sea → Luzon Strait → Pacific → US West Coast
- China, South Korea, Japan → Los Angeles, Long Beach, Seattle
Intra-Asian Routes
- China ↔ Southeast Asia (massive manufacturing supply chains)
- Singapore ↔ Hong Kong, Shanghai, Kaohsiung
- Regional feeder networks serving Vietnam, Thailand, Indonesia
Major South China Sea Ports
China:
- Shanghai: World's busiest port — 47M+ TEU/year
- Shenzhen (Yantian): 29M+ TEU/year
- Guangzhou (Nansha): 25M+ TEU/year
- Hong Kong: ~18M TEU/year; major transshipment hub
Southeast Asia:
- Singapore: World's largest transshipment hub — 37M+ TEU/year
- Port Klang, Malaysia: 13M+ TEU/year
- Tanjung Pelepas, Malaysia: Major transshipment center
- Manila, Philippines: 5M+ TEU/year
- Ho Chi Minh City (Cái Mép), Vietnam: 7M+ TEU; rapidly growing
China's Dominance: Among the world's top 10 container ports, 7 are located in China or are Chinese-operated. The South China Sea is effectively the front yard of the world's largest trading nation, giving China enormous strategic leverage over global supply chains.
Geopolitics, Resources & Environment
Physical Characteristics
- Area: 3.5 million km²
- Average depth: ~1,212 meters
- Maximum depth: 5,559 m (West Luzon Basin)
- Monsoon-influenced climate; typhoon prone
- Water temperature: 26–30°C at surface
Territorial Disputes
The South China Sea is one of the world's most contested maritime regions:
Nine-Dash Line: China claims roughly 90% of the South China Sea via the historically and legally controversial "nine-dash line." The 2016 UNCLOS arbitral tribunal ruled this claim invalid, but China has rejected the ruling. The dispute involves overlapping claims from Vietnam, the Philippines, Malaysia, Brunei, and Taiwan — and has led to military build-ups, artificial island construction, and repeated confrontations.
- China has built 7 artificial island military installations in the Spratly Islands
- Philippines vs China: repeated confrontations near Second Thomas Shoal
- Vietnam: regular confrontations with Chinese coast guard near Paracel Islands
- US, Australia, and others conduct Freedom of Navigation Operations (FONOPs)
- Risk of miscalculation remains a major concern for regional stability
Natural Resources
- Estimated 125 trillion cubic feet of natural gas (US EIA)
- Estimated 11 billion barrels of oil
- Some Chinese estimates far higher (though disputed)
- Rich fishing grounds; vital food source for 3.7 billion people in the region
- Illegal, unreported fishing is a major transnational issue
Typhoon Season & Navigation Risks
- South China Sea is primary typhoon formation and track zone
- Typhoon season: May–November; peak July–October
- Average 10–15 typhoons form annually; many intensify over warm SCS waters
- Typhoon Haiyan (2013): one of the strongest on record; devastated Philippines
- Ships must monitor and avoid typhoon tracks; routing services essential
Environmental Issues
- Coral triangle covers part of South China Sea: world's richest marine biodiversity
- Chinese dredging for artificial islands destroyed 160+ km² of coral reefs
- Severe overfishing by all regional nations
- Oil spills risk from high vessel traffic density
- Marine plastic pollution: Southeast Asian rivers are world's largest source of ocean plastic