The case was found when the boats were filmed by a local resident. The clip then went viral on Facebook.
The two tourist boats have been fined VND8 million (USD347.82) for throwing votive papers into the Huong River.
After that, local authorities launched an investigation into the case and identified the boat owners.
Nguyen Xuan Son, Director of the provincial Department of Information and Communications, said that at the police station, boat owners admitted to littering.
Earlier, a man in Hue City was also fined for throwing votive papers into the Huong River.
