Opinion Fionnuala O ConnorPrettied up now but still in the end a tidal flow across sloblands, the Lagan runs through Belfast as it has through the ages.
A hopeless river, really, the historians say, couldn't provide a decent harbour without wholesale dredging: it was two other long-forgotten and culverted rivers that powered the mills and built great industries.
Yet still the Lagan flows, while the Farset and Blackwater burrow underground.
Today's urban geography is the outcome of physical features exploited and reshaped through centuries.
The feeling its citizens have for the Lagan are as subdued as the relationship many have with Belfast.
How can it be otherwise? Where the river meets Belfast Lough is where shipyard and dockland serviced commerce and made merchants rich, where the most stable and best-paid work was dominated by Protestants, where at moments of political high tension Catholics were driven into the water and out of the yard, where the Catholic navvies who built the docks fought shipyard men, and where James Larkin briefly united workers in defence of the most basic rights.
To the questing eye, the landscape is spiked with violent memory, as much witness to the best and worst of human endeavour as this first decade of uneasy peace.
On these sunlit last days of summer, as school terms settle in and republicanism and unionism square up to each other yet again but through the medium of politics rather than violence, there are still three guided boat tours a day from the river-mouth to Stranmillis in affluent south Belfast and back.
You wouldn't expect a potted history of conflict to come booming over the boat's megaphone and you don't get it. There is a dogged and vocal resistance to hearing anything but the most bland version of the past in public, shared space.
If the first tour had kicked off with a spiky retrospective, there would never have been a second. The boat tour does the very best it can. There are moments when the cliffs of waterside apartments and brutalist office-blocks begin to recede, when the hills curve, clear and blue, round the horizon, children wave from the cleaned-up riverside path and "recovering" reed-beds nod in the breeze.
"Good to see the reeds coming back," says the boatman. "They help to clean the water."
On Wednesday a bunch of middle-aged to elderly Southerners came off the middle boat of the day looking pleased, posing for smiling photos before they moved off.
The last boat managed to gather up a dozen only. One of the first to board was a 26-year-old from Madrid, taking a day out of working in Dublin to see Belfast, dutifully following the tourist board's itinerary.
He had just done the City Hall and was headed next for the Falls and the Shankill to see murals.
He hoped his credit card and euros would see him through. Tourists keen on city-centre sights are still rare enough to be cherishable. The boatman insisted he have the trip for free.
In an hour and a half you flick past the most striking new buildings along the banks, see the handiwork of city fathers and traces of bygone landowners, hear that river management has revived fish and flora and controlled the stink of ages, up to a point.
With a degree of stoicism the riverboat's owner, Derek Booker, told the BBC last Tuesday that uninviting sights sometimes greeted people around the embarkation pontoons.
He was commenting on the announcement of a new tunnel intended, yet again, to keep sewage out of the Lagan.
But on Wednesday there was clear water round the pontoon at the flashy new Lookout Centre, where schoolchildren delight in close-ups of the expensive weir and then board the boat, worksheets at the ready: "You will be passing underneath seven bridges. Listen carefully for their names."
At the back of the sheet is the list, in the order the boat passes them with the dates when they were built: "Queen Elizabeth II bridge (1966); Queen's Bridge, named for Queen Victoria (1842); The Lagan Viaduct (1995); Albert Bridge (1890); Ormeau Bridge (1863); King's Bridge (1910); Governor's Bridge (1970s)."
Like the rest of the names mentioned in the tour - Lady Ann Mornington and her son, the Duke of Wellington, Harland and Wolff, former lords mayor - the list resonates with proper pride for the community who have always thought of Belfast as their capital.
For descendants of the navvies and deep-sea dockers, by contrast, it has some of the old flavour of exclusion.
There might be consolation in the only neutral name, derived from the language imprinted on the physical landscape underlying the built one - the "Lagan Viaduct".
But none of that's the kind of thing to be said aloud to tourists: or at least not yet.