According to Tuoi Tre, the boat, operated by Anh Duong Co. Ltd., burst into flames near the bay's Titov Island after spending the night in the area. The vessel was on its way back to Tuan Chau Port at the time.
Rescue boats hurried to the scene, according to the news source, and safely brought all 21 people from the burning boat to shore. Vu Van Dien, deputy chairman of Quang Ninh province, has ordered an immediate inspection of fire safety on all boats operating on the bay following the incident, Tuoi Tre reports.
Huge numbers of tour boats and ships ply the waters of Ha Long, and this is far from the first time one has caught fire with guests on board. Last May, flames tore through a ship shortly after it arrived at Tuan Chau, forcing 36 tourists and their guide to jump overboard.
In February 2015, another ship went up in flames near Titov Island, leading to the rescue of 16 tourists, seven crew members, a guide and a steward.
[Photo via Tuoi Tre]