Our Vietnamese tour guide glares at the morning mist as if it's a familiar enemy as he recounts the destruction of a cruise ship recently lost in bad weather.

We sit on a motorised boat, waiting to be transported to our own cruise ship, the White Dolphin.

"I check the weather report. It going to clear," he says convincingly.

Hope hangs on the dozen faces turned his way.

Bad weather is bad for business; the valuable tourist trade dries up when the weather is wet.

It's easy to understand the pressure on the Halong Bay tour operators: this isn't a backyard rice paddy we've forked out to see, but one of the New Seven Wonders of Nature. Named one of the 10 best boat journeys in the world by Lonely Planet, since its World Heritage listing by UNESCO in 1994, tourists have been pouring in.

The mist clears and one-by-one, we stagger up the gangplank onto the Greek colonnaded, White Dolphin. Like all the other tourist vessels in the bay, it's painted white. The accidental sinking of a tourist vessel in February 2011, where 12 people died, led to increased safety regulations, including the hospital-chic cruise ship colouring.

It is silent and still in Halong Bay, something Australians don't always associate with the sea. Halong Bay is more profound than picturesque and more graceful than rugged. You could hear a seamstress in Hoi An drop a pin. Only the low puttering of the tourist boats disrupts the silence.

Replace tourist vessels with armadas and you're reaching into the dark history of Halong Bay. Ancient and modern naval battles have been waged on these waters, with the resilient Vietnamese surviving Chinese, Dutch, French, and American invaders, among others. The area's earliest inhabitants go back as far as 18,000 BC and the beginnings of the ancient Soi Nhu culture. The geological age of the bay itself is estimated at about 300 million years.

Engraved over millions of years thanks to its soluble bedrock, in geological terms Halong Bay is the most dramatic and extensive example of marine-invaded tower karst formation in the world. Over its 1550 square kilometres, this magical bay within the Gulf of Tonkin harbours about 2000 small islands as well as caves and grottoes, hidden inland lakes, light forests, rock arches, beaches and lagoons. Species in the area include 200 types of migrating birds, 232 coral species, reptiles, deer, weasels, squirrels, langurs and monkeys.

After lunch, we board kayaks for our first adventure off the ship - a water-borne tour of the small, floating Vung Vieng fishing village, a collection of enchanting linked wooden floating homes.

A dog barks and jumps all over a man as he alights from his boat onto the verandah of his floating home. Kids chase each other across the platforms that link the houses. Washing flaps in the air. A man sleeps on a hammock in the sun. The soft chanting of children comes from a small floating building that serves as a school.

Within the bay, about 1600 residents live in similar floating villages, earning a living from fishing and aquaculture. Oblivious to us, they go about their lives seemingly untouched by their encounters with the curious, sometimes ogling, tourists.

Everyone bombards the tour guide with 21st-century questions.

"What happens when there's a storm? Is it dangerous for them?" a Brazilian girl asks.

"The houses just go up and down with the waves," our tour guide explains. "If a typhoon is coming, they can get on the boat and take the boat to a safe place," he adds.

The day ends with the bravest of our group dive-bombing off the top of the Dolphin into the sea, while others treat themselves to a magenta sunset as they recline on deck chairs.

The final activity of the two-day cruise is a visit to Bo Hon Island to see Hang Sung Sot (the Surprise Cave).

Containing three chambers of increasing size, the cave is accessed by steps leading up the side of the island. The climb gives views down to a lime-green inland lake and sweeping vistas of the bay.

Following our guide through the illuminated chambers, we learn how the bay has served as a sanctuary for the Vietnamese. Locals used this cave as a refuge from typhoons and our guide points out a formation supposedly shaped like a Buddha - the focus of many prayers.

Standing within the dark setting of the Surprise Cave, our guide tells the legend of Halong Bay, which translates as "descending dragon bay" in Vietnamese.

In response to the prayers of the besieged Vietnamese, the Gods "sent dragon family who fly to here … they opened their mouths and thousands of dragon pearls became like islands today. When the boats came from the sea they could not find the channels … they could not get inside the land. They had to go back to the sea and they could not control the Vietnamese."

On the ride back to the wharf, I find myself scanning the sea for dragons. If this mythical creature did exist, it would surely be here in this ancient kingdom of silk water and precipitous peaks.

TRIP NOTES

GETTING THERE

Although it's technically possible to sail to Halong Bay via China, it is usually accessed from Hanoi. Halong city is the gateway to the bay. Direct Flights to Hanoi from Australia are available with Virgin Australia and Vietnam Airlines. Australians require a visa and at least six months' validity on their passport to enter Vietnam.

See vietnamembassy.org.au.

STAYING THERE

Cruise operators are plentiful, from budget to high-end. A two-day or longer cruise is recommended, to view the bay at sunset, sunrise and overnight and during different weather conditions. Typically, everything but drinks is included.

The best months to visit are September to November and March to May, avoiding the tropical storms between May and September. Check that your tour boat offers refunds in the event of a cancellation forced by weather.

SEE+ DO

Top choices in Halong Bay are: The hospital cave, Cat Ba National Park, sailing overnight in an Asian-style junk, visiting a floating fishing village.

MORE INFORMATION

halongbay.info