Underwater archaeological sites and wreck sites provide important information on the history of nations and mankind. The Gulf of Siam is one such important site, having been a territorial waterway to and from the Malay Peninsula since the 4th and 5th centuries. Despite reasonably stable weather in the Gulf, conditions could be perilous. The number of shipwrecks to be found here, many of which are still intact owing to the relatively good underwater conditions that enable material objects to be preserved, reflects the risks. Much can be learned from these wrecks, including details of the ships’ structures (e.g. type of wood and construction techniques), the merchandise (e.g. ceramics, celadon, rice, horns, wax and earthen utility wares) and other artefacts (e.g. kitchen utensils and musical instruments). The discovery of human traces, however, is rare since most passengers were either saved, carried away, or consumed by sea creatures.