Lake Chimay or Chiamay, also known by numerous other names, was a fictitious lake or marsh which appeared in European maps of Asia throughout the Age of Discovery. Originating from accounts of Portuguese exploration of Indochina, it was believed to be an enormous lake about 1,100 kilometers (680 mi) inland from which several of the major rivers of Bangladesh, Burma, and Thailand flowed. It continued to appear in European maps, gazetteers, and encyclopedias into the late 18th century.