In my kayak, I can glide close to limestone pinnacles and bob inside hidden lagoons instead of savouring the seascape from afar, like a postcard.
By paddling to places that larger vessels cannot squeeze into, I have much freedom to unwrap the scenery at my pace, cove by cove and islet by islet. It is an intimate brush with Vietnam's remote northern coast.
We are exploring Bai Tu Long Bay, just north of its more glamorous sibling Halong Bay, a Unesco-listed World Heritage Site since 1994.
Both bays belong to the same sunken limestone plateau that stretches to the Chinese border up north - and they are equally beautiful. I know this from comparing the scenery of both bays from our 15-cabin cruise ship, Treasure Junk.
Our vessel first cruises through Halong Bay, then steers north and, in a couple of hours, we arrive in untouched Bai Tu Long Bay for two days of leisurely kayaking. Here, it is quiet and still not much developed, as we have forsaken the crowded cruising routes of Halong Bay.
Our first day, starting at 3.30pm, we hop into double-seater kayaks and, in moments we are moving over jade-green water.
Kayaking for a couple of hours on placid waves, with breaks, is fairly easy, it turns out. It helps that my paddling partner is a strong Kiwi woman.
Kayaking melds sight, sound and sensation. I love the changing scenes of fantastical limestone spires and islands all around, the incessant sound of waves and crickets, and the sense that we have slipped across a watery border into an Asian myth.
At a secluded beach, we rest, and it is just us. In this folkloric setting, our adventure guide Ngo Trong, 28, starts to tell stories about dragons and Chinese invaders.
Halong means "descending dragon" and the legendary liberator had defended Vietnam from its perpetual enemy, China.
Myths often have some basis in historical fact. The dragon myth, I will surmise, expresses hopes of divine intervention against a much bigger enemy.
In May, when I visit, the myth takes on a contemporary flavour. Days earlier, anti-Chinese rioters had risen up in parts of Vietnam, incensed that China deployed its Haiyang Shiyou 981 oil rig to disputed waters in the South China Sea.
Though China looms over the horizon, these troubles seem far away in isolated Bai Tu Long, which means "the dragon parts from its offspring". Many islands here have names that end in "long" or dragon in Vietnamese.
By the time we leave our small island, it is misty in the distance and the evening light has a soft luminosity.
Still, it is not a total idyll here for the guests, who include a policewoman and a sheep farmer from Invercargill in New Zealand, and a pianist and lawyer from London.
While the water looks like liquid emerald, swathes of it are polluted. Because our tour operator, Handspan Travel Indochina (www.handspan.com) is community-minded, they ask guests to fish out floating marine debris flowing from the river, shipping vessels or, as some Vietnamese like to allege, from China.
We are industrious and pick up dirty styrofoam, plastic bottles, slippers, toys, sweet wrappers and woefully more, stashing the junk in nets or strapping the chunkier pieces to our kayaks till they look like floating garbage trucks.
Handspan, which has operated in Bai Tu Long for five years, also organises volunteers to do annual clean-ups of this bay, since the authorities focus on scouring famous Halong Bay. The Vietnamese company has also built 30 schools in Bai Tu Long.
At the break of dawn on the second day, our ship starts its voyage to the centre of Halong Bay and moors there. Again we do not linger in touristy Halong to kayak - a smaller support boat deposits us further south in Lan Ha Bay.
A trio of scenic, shallow bays - Halong, Bai Tu Long, where we kayak the first day, and now Lan Ha - make up the Gulf of Tonkin. Three thousand limestone islands and islets dot the gulf.
Today, in Lan Ha Bay, we glide between some of these sheer, grey limestone cliffs that are splashed with the intense green of creepers and clinging plants.
In many places, the cliffs frame the landscape like colossal doorways. We paddle towards these portals, wondering what other dramatic, drowned peaks lie beyond.
The islands have fanciful names like Frog and Teapot, labelled by local fishermen for their passing resemblance to creatures, objects and phenomena that fill their life.
I love the play of shadows, cast by cliffs, on the shimmering water. It is hot, about 30 deg C, but we have a refreshing breeze. And I also find it uplifting to be out at sea, anywhere, even if there is some taint of human presence and detritus.
Once, we have to paddle fast against the wind, and our guide makes it fun by turning it into a race.
Caves and secret lagoons abound in the bay. Our experienced guide has scrutinised the tide tables, so we will not be marooned inside when the tide changes.
We strap on head lamps to enter our first cave. It is 200m deep, but too shallow to paddle beyond 100m or so. We enjoy the silence and novelty.
A few minutes later, we hear the voices of locals who have walked deeper inside the cave to collect oysters.
We paddle next to a "light cave", which is really an immense natural arch that links the bay with a hidden lagoon.
Portuguese television journalist Sonia Lacerda, 39, says the landscape makes her feel tiny and engenders "a new respect for nature".
For Mr Daniel Parren, 32, a Dutch system architect, kayaking is preferable to cruising for it brings the phenomenal landscape closer to him.
On our third and final morning, we do not kayak but are rowed instead in Vung Vieng, a floating village nestled in a lagoon and under immense cliffs. The fisherfolk live in wildly scenic corners of the bay, sheltered from typhoons.
Vietnamese villagers, thin and strong, row us in bamboo boats under the towering cliffs and out to the blustery sea. We also stop by their floating houses set on plastic barrels and styrofoam.
Neighbours relax over morning tea served in ceramic cups, while dogs patrol each shack. Even the toddlers are sure-footed as they play on the planks.
Our group has come prepared with gifts of exercise books, crayons and snacks for the children, who accept them shyly, one sign that the place is not yet over-run by candy-bearing tourist hordes.
Boats from the mainland collect the fishermen's catch every day. The villagers also farm shrimp, clams and oysters.
At a little centre run by Vinapearl (www.vinapearl.vn), a pearl company jointly set up by Vietnam and Japan, we get a primer on cultured pearls.
While I know the basics already, I can now observe how oyster nets are submerged in 1 to 3m of water where plankton is densest.
Only a fraction of pearls meet jewellery standards. Imperfect pearls may be ground into powder for medicine or cosmetics.
Apart from kayaking, we have fun activities on our ship, or close to it. It is squid season so we fish for our calamari at night.
Attracted to lamps on our boat, the squid rise to the bait like tiny apparitions, all silvery, shimmery and elusive. Many times they tug at my fishing line, flail as I pull them in, and plop right back into the water.
It is much easier to just swim, which immerses me in wraparound scenery just before the evening light disappears. But when an alert crew member on the ship spies jellyfish, my swim promptly ends.
The guests and I dine on the freshest seafood. I relish a clear, spicy seafood soup fragrant with herbs, steamed shrimp served with sea salt and a squeeze of lime, and Vietnamese drip coffee.
Often, we gaze at the mobile tapestry of pinnacles and waves from the deck or through huge windows in our spacious, air-conditioned cabins. The Treasure Junk cruises at a relaxed pace of 7 to 8kmh.
Ms Jutta Schwerdtle, 33, a German brand manager, smiles each time she kayaks and thinks the voyage is a perfect combination of nature, action and mystery. "The kayaks bring us so close to nature, and there's peace and freedom. That's the secret of my smile,'' says Ms Schwerdtle, who also loves to mountain-bike, trek, kite-surf and ski.
"The bay is full of mystique, with legends about a dragon and its babies. I like the explanation of life through fairy tales, instead of Western rationalisation."
And so we unwrap the meanings and secret layers of this landscape, when we kayak and enter a less-known Vietnam.
Follow Lee Siew Hua on Twitter @STsiewhua
This is the second of a five-part weekly series. Next week: Via Ferrata adventure on Mount Kinabalu
Kayaks are small, arm-powered vessels inspired by the seal-skin boats used by Eskimo hunters in the Arctic. Today, kayaks are a relaxing way to explore seas and lakes while burning calories and boosting fitness.
My tour operator Handspan Travel Indochina supplies Maine-made Necky fibreglass kayaks, paddles and life-vests, so my packing list is compact.
I pack open-fingered paddling gloves to prevent blisters, a broad-brimmed hat, sunglasses, sunblock, water sandals, quick-dry clothing and swimsuit.
My camera and phone are stashed in a "dry sack" which seals for water-tightness.
Kayaking requires upper body strength - mainly the core muscles, not just the arms.
For a powerful stroke, paddlers rotate the torso and work the shoulders. They fire up the core, which includes the large muscles of the abdomen, hips and lower back.
To prepare, I add more crunches and planks to my workouts to build the core, besides going for my weekly pilates class. I tone my arms with light weights and push-ups.
Some cardio-vascular endurance is needed, so I go for a few aerobics classes.
Look for a reputable operator that is safetyconscious, and be aware of the risks of kayaking. An experienced kayak guide will read tide tables, so kayakers will not be marooned in caves or lagoons when the tides change. Kayakers who try to scramble out of tricky situations can cut themselves on barnacles.
With preparation and a spirit of adventure, a kayak holiday combines fun and fitness in lessexplored realms.
Apart from the Halong archipelago, exotic kayak trips include paddling among penguins in New Zealand, observing whale sharks in Mexico, and exploring Alaska's glacial fjords.
Lee Siew Hua