The vessel sank in calm weather one kilometer southeast of Ti Top island, Hung said by phone from Halong. The dead included eleven visitors from the United States, France, Japan, Australia, Switzerland, Sweden, Russia and the United Kingdom, he said.

Halong Bay, dotted with more than a thousand limestone islands, is a United Nations World Heritage Site that attracted 48,000 visitors during the Lunar New Year week last month, according to the Vietnam National Administration of Tourism’s website. The boat capsize, the second since 2009, comes as Vietnam’s tourism industry aims to double its contribution to the nation’s gross domestic product to 8 percent by 2020.

Twenty-seven passengers and crew were on board the boat, run by Quang Ninh-based Truong Hai Co. Ltd, according to Hung. Fifteen people were rescued, including six crew members, he said.

An initial investigation indicates there were problems with the boat’s hull, according to a statement on the Quang Ninh provincial government website. “Crew members and staff tried their best to deal with the water that flooded in and alerted all passengers on board,” the statement said.

There were 19 foreigners on board, according to the website and of the dead, 10 were foreigners and two Vietnamese. Four calls to Hung to clarify the discrepancy were unanswered.

Officials from Truong Hai could not be reached for comment when called at the company’s office, as they were “out on the scene,” said a woman who answered the phone but declined to identify herself.

By Nguyen Kieu Giang & Diep Ngoc Pham - Bloomberg - February 17, 2011