Passenger ships will soon be banned from staying overnight in Ha Long and Bai Tu Long bays, authorities in the northern province of Quang Ninh said.
In the near future, only daytime travel will be allowed in the sea.
The move is part of a local program that also intends to replace wooden boats with metal boats over the next five years.
The authorities expected that the program will help enhance tourism service quality and safety.
Currently, 553 tourist ships operate across the two bays, 202 of which dock overnight.
In 2015, Ha Long and Bai Tu Long bays welcomed about 2.5 million tourists. The fleet can serve a maximum of 10 million passengers, meaning there are too many ships.
Quang Ninh recently issued a temporary regulation that allows wooden ships to operate in the bays for a maximum of 15 years, as opposed to the regulated 25 years.