The agreement-signing ceremony was held in Belgrade.
According to the Serbian news agency Beta, the purpose of the project is to develop fishing and hunting tourism as well as rural and ecological tourism in the Sava basin.
The project's co-ordinator, Petar Nikolic, said the atlas would provide important information on navigation along the Sava as well as about places of tourist interest in the area.
The atlas will be published in the languages of the countries-signatories.