The Strait of Malacca is said to be the longest strait in the world. The Strait of Malacca is a narrow stretch of water, 800 kilometres (500 mile) long. Strait of Malacca, waterway connecting the Andaman Sea (Indian Ocean) and the South China Sea (Pacific Ocean). Strait of Malacca separates Malaysia and Sumatra (Indonesia) It is the main shipping channel between the Indian Ocean and the Pacific Ocean*