At one point, the Ngo Dong River flows between two impressive bluffs
An astonishing 1,300 manned rowing boats are used to take tourists up the Ngo Dong River to Tam Coc and back.
From the village of Van Lam in Ninh Binh Province, it's a two-hour trip along the river to the three limestone caverns that give Tam Coc its name.
While we're on the subject, ngo dong is the Vietnamese name of the beautiful wutong tree, or Sterculia platanifolia, not that we saw any on our journey. The river gets its name from the enchanting scenery.
We were keen with anticipation when we arrived at the wharf in Van Lam, about a hundred kilometers south of Hanoi.
The paddy fields all around were yellow from the ripe rice that was being harvested, and seemed to lend their tinge to the water. We were fortunate to be there at the best of times.
The flimsy looking craft at Vung Tram Pier resembled leaves floating on the water. Each had two oars secured to the gunwales with rope at their pivot points rather than with rowlocks. There were also paddles for the passengers to speed things along if they so desired.
We asked a waiting oarsman why motor boats weren't used, and he replied that they were noisy and would pollute the river. Anyway, the whole idea was to take a peaceful cruise and enjoy the sounds and serenity of nature as much as the stunning sights, so a motor boat would be all wrong.
Our tickets cost us VND50,000 each: VND20,000 for the boat fare and VND30,000 for admission to Tam Coc. Each small scow carried four people, and the rowers got VND70,000 each for their services.
Our ship's master, 32-year-old Chu Anh Khanh, told us that he'd had to wait ten days for his latest turn on the water (they use a roster).
Tam Coc in Ninh Hai Commune, Hoa Lu District is among Vietnam's most famous scenic attractions. The Ngo Dong River that runs past the three grottoes winds its way between abrupt limestone karsts like the peaks that characterize Ha Long Bay and much of the country's north.
We visited the three caves in turn, actually going inside in the boat with the roof only inches above our heads in places. The first cave, Hang Ca, was the longest at 127 meters. Water dripped constantly from the stalactites that hung from the limestone ceiling, making the air very cool.
The second and third caves are named Hang Hai and Hang Ba. In English, that's Cave Two and Cave Three. Outside Hang Ba were dozens of boats selling soft drinks, lotus buds, bananas, pineapples and other refreshments and assorted touristy merchandise.
One of our rowers was a teenager named Hai, who wore a large scarf on her head as protection from the strong sun. There was also an old oarsman called Loc with white hair and a beard who said he was 75 years old. Many people took pictures of Loc as he rowed.
To make it possible for the whole of Ninh Hai Commune to benefit, Tam Coc's administrators permit any household with a registered boat to carry paying tourists along the river and into the caves. The 1,300 registered boats are numbered and their owners must wait for their turn.
How long do they have to wait? The calculation is simple.
If there are many tourists and 300 boats are used every day, they have to wait four days or so; if there are fewer tourists and only 100 boats are needed, they have to wait 13 days for their turn.
In between shifts on the river, they can do related work like carrying luggage or selling food to the tourists. There is one other rule: The boats that supply tourists with souvenirs, refreshments and food are not allowed to carry paying passengers.
A girl named An told us that most everyone in Ninh Hai could row a boat with their legs. Since it's a long journey up the river and back, the crews use their arms to row for half the time, and their legs for the other half. Otherwise they would get too tired and sore.
The change from arms to legs is always done when the boats pass Thai Vy Temple, originally built in the thirteenth century and dedicated to King Tran Thai Tong. It's a striking location with the grandeur of the Cam Son Mountains as a backdrop.
"It's not easy rowing a boat with your legs. If it's not done right, the boat can capsize," An told us moments before a nearby boat suddenly veered off course and plowed into a rice paddy, from where it was extricated with the help of a third party.
After visiting Hang Ba, we were surprised to see a herd of milk goats with white fur scrambling up the steep mountainside foraging for food.
We were told that the goats were domesticated and that, if someone wanted to buy one, their owner would catch one. Apparently the flesh of Ninh Binh's milk goats is the provincial specialty.
For me, it felt like I'd been transported to another world as I gazed at the legs of the friendly rowers moving back and forth to propel the boat past yellow fields of mature rice on both sides of the romantic Ngo Dong River.
Our oarsmen and women were great tourist guides in that they didn't hurry us along but instead gave us the time to get the most out of our journey and tell us stories about life on the Ngo Dong River. Above all, the picture that sticks in my mind is the skilful way they rowed with their legs.
The enchantment of Tam Coc will stay with me for a long time.