About 18 meters below the sea off Rayong province, 15 divers from seven countries are exploring a wooden shipwreck.
The exploration is part of Unesco's six-week training on underwater cultural heritage preservation.
The divers are from Cambodia, Indonesia, Laos, Malaysia, the Philippines, Sri Lanka and Thailand.
They have been picked for an underwater heritage protection programme organised by the United Nations Education, Scientific, and Cultural Organisation (Unesco) and the Fine Arts Department's Underwater Archaeology Division (UAD) which runs from Oct 26 to Dec 6.
Division head Erbprem Vatcharangkul said Thailand has 64 underwater archaeological sites. He said all of them, especially those in shallow water, were under threat from treasure hunters.
Protection of the sites required well-trained staff and cooperation from local people, including fishermen.
Other countries in the Asia-Pacific region face similar problems which prompted Unesco to set up the regional field training center to promote underwater heritage protection in the region and to exchange conservation information.