Tour guide Pham Huy Trung's photographs offer a glimpse of the unique charm of Ha Long Bay, a UNESCO natural heritage site in northern Vietnam. 

At around 3 a.m. fishing boats gather at a wharf in Ha Long Bay, adjacent to Hon Gai seafood market, after a long night out at sea. The wholesale market is open from early morning until 10 a.m., but its busiest time is between 7 a.m. and 9 a.m. when traders rush to buy the freshest fish.

Rocky islets amid mist at 6:30 a.m.

The bay in Ha Long, which literally means "descending dragons," was formed by millions of years of geological activity, which created thousands of islets. It became a fixture on the world tourism map after being recognized as a world heritage site by UNESCO in 1994.

A boat on the emerald green waters surrounded by limestone karst.

While hordes of people come to explore the majestic beauty of the bay, not many know about the legend and mystery associated with it.

Legend has it that in the earliest days of the nation Vietnamese had to fight off hostile invaders attempting to enter through the sea. The Jade Emperor sent the Mother Dragon and her children to help the Vietnamese defeat their enemies.

The mother dragon and her children incinerated the enemies with their fire and emeralds, which scattered around the sea, creating an impassable barrier which sank the enemy’s battle fleet. Finally the invaders were repelled, and peace returned to the country. When the battle ended, the dragons did not return to heaven and instead decided to stay there.

Besides luxury cruise ships, visitors can see the image of fishermen sailing on small boats to earn a daily living in Ha Long. Tour boats often stop at floating houses for visitors to get a glimpse of how the fishermen live. 

Sunset over the bay.

Most of the islets in Ha Long Bay are uninhabited; many of them are inaccessible to human visitors due to their sheer limestone cliffs.

British travel magazine Rough Guides last month listed Ha Long Bay
as one of the 100 most beautiful places to visit next year.

In the "The Rough Guides to the 100 Best Places on Earth," it describes "the scattering of limestone pinnacles jutting out of the smooth waters of Ha Long Bay," around four hours east of Hanoi, as an "incredible sight."

Cruise ships lit up at night on the bay.

An overnight cruise trip has been recommended as a "must-try" travel experience in Asia by  the U.S. news site Business Insider.