More than half of the world's annual merchant fleet tonnage passes through the Straits of Malacca, Sunda, and Lombok, with the majority continuing on into the South China Sea (see map). Oil flows through the Straits of Malacca leading into the South China Sea are three times greater than through the Suez Canal/Sumed Pipeline, and fifteen times greater than oil flows through the Panama Canal. Virtually all shipping that passes through the Malacca and Sunda Straits must pass near the Spratly Islands. The other major shipping lane in the region uses the Lombok and Makassar Straits, and continues into the Philippine Sea. Except for north-south traffic from Australia, the Philippine Sea is not used as extensively as the Strait of Malacca and the South China Sea, since for most voyages the Philippine Sea represents a longer voyage by several hundred miles.

Shipping (by tonnage) in the South China Sea is dominated by raw materials en route to East Asian countries. Tonnage via Malacca and the Spratly Islands is dominated by liquid bulk such as crude oil and liquefied natural gas (LNG), with dry bulk (mostly coal and iron ore) in second place. Nearly two-thirds of the tonnage passing through the Straits of Malacca, and half of the volume passing through the Spratly Islands, is crude oil from the Persian Gulf. Oil flows through the Straits of Malacca were 10.3 million barrels per day in 2002, and rising Asian oil demand could almost double these flows over the next two decades.

Northeast Asian nations are heavily dependent upon energy shipments through the South China Sea. More than 80 percent of the crude oil supplies for Japan, South Korea, and Taiwan flow through the Sea from the Middle East, Africa, and South China Sea nations such as Indonesia and Malaysia. LNG (above) and coal from Indonesia, South Africa, and Vietnam are also shipped via this route. As a result, about two-thirds of South Korean energy supplies, and almost 60 percent of Japan and Taiwan's energy supplies flow through the Sea.