Thousands of tourists found themselves stranded at Bai Chay Port after around 500 tourist boats shut down their operations, on Friday morning.
The holdup at Ha Long Bay's major passenger port was created by a knew set of guidelines known as the 716 Decision.
The Quang Ninh Province People's Committee put the rules into effect on Friday.
They dictate that tourist boats must satisfy certain design and staff requirements.
Trinh Dang Thanh, deputy director of the Quang Ninh Department of Culture, Sports and Tourism, described the shut-down as voluntary; complaint boats and ships had been allowed to enter the bay.
Several boat owners said it would take time for them to come into line with the new regulations.
Do Manh Hung, a port official, said they had yet to receive any announcement about the implementation of the 716 Decision.
Many of the stranded tourists had come up from the south and hundreds of visiting tourists were among them.
Last February, Quang Ninh authorities tightened rules on tourist boat management following a major accident that killed 12 tourists (including 10 foreigners).
Last month, a boat with nearly 30 tourists onboard sank after another vessel crashed into it on Ha Long Bay, but no casualties were reported.