The country's preeminent port was Bangkok, which in the early 1980s handled 98 percent of imports and 65 percent of exports as well as about 40 percent of coastal traffic. More than 4,000 foreign vessels were reported to have called at Bangkok in 1983, and about 24 million tons of cargo were handled, including coastal cargo. Two other ports of some significance in international trade were Si Racha and Sattahip, both located southeast of Bangkok on the Gulf of Thailand. Both ports were used primarily for exporting agricultural products. Sattahip's deep-water naval facility was also used to handle imports of heavy equipment.

The port of Bangkok had experienced continuous growth since the 1950s, and, through loans from the World Bank, its facilities had been substantially expanded to handle the increased traffic. A major drawback of the port was its limitation on vessel size and draft, which forced ships of more than 10,000 tons or 8.5- meter draft to offload at the mouth of the Chao Phraya, some 27 kilometers downstream. As part of the Eastern Seaboard Development Program, the government in 1986 approved plans to build a new deep-water port at Laem Chabang in Chon Buri Province to supplement Bangkok's Khlong Toei port. An industrial estate was to be built close to the port area for export-oriented industries, such as electronics, and for agro-based industries, such as food processing and rubber products. Under the same program, a new port and industrial park was to be constructed at Mapthaphut to serve the petrochemical, fertilizer, and soda ash industries.

Some thirty smaller ports were found along the Gulf of Thailand and the Andaman Sea. About half were fishing ports, and the remainder served multiple purposes, including coastal services, export and import functions, and fisheries operations. Coastal operations were in general small. In the early 1980s, the government also had under consideration development of deep-water ports at Songkhla on the east coast of the peninsula, through which rubber was exported, and Phuket on the west coast. Phuket served as an outlet for both tin and rubber exports.

In 1985 the Thai merchant fleet consisted of 71 freighters, 2 bulk carriers, and 25 tankers, totaling roughly 700,000 tons. Regular cargo service was provided between Thailand and Japan, and one shipping company made regular calls at West European ports. An unknown number of small coastal vessels conducted trade with Malaysia and Singapore.

Data as of September 1987