"Breakfast at sea," Graham announced the next morning, standing at the wheel. We made a sharp turn through downtown Trebes, passing an old man in suspenders standing in his backyard, and entered again the long green tunnel. Shortly, another delicious egg dish made its way up from the kitchen.

Three hours and six locks later, we arrived in Carcassonne. It was strange and a little disconcerting to see apartment houses and graffiti again, though the soothing plane trees had not abandoned us. We docked next to a stand, and took our turns heading into town, each couple carrying a small shopping list.

Hania and I climbed the hill, took a walk through the ancient citadel, admired the stained glass windows of Basilica St.-Nazaire. Heading back into town, I read the graffiti on the stone footpath: "When an old man dies, a library burns."

We found a health food store, though there were no fresh gluten-free breads. The woman at the cash register said quite a few people come in with children who become sick from eating baguettes. "We say in this store that flour is public enemy No. 1." It seemed a strange sentiment to hear in France.

Then we went to buy cheese and sausage. The man gave me a taste of saucisson Roquefort. A wedge of fat lodged between my teeth and stayed there till I got back to the boat. French food, the food that gets you back.

In the supermarche near the canal, we bought milk, ham and eggs. Yes, we were tourists, but we were also grocery shoppers. It gave us, I thought, a certain prestige. A fellow boater, an Australian, was trying to convey to a young employee that he was looking for peanuts.

"Cacahuetes," I said.

"Ah," the store clerk said, with the joy of the newly enlightened, "peanuts c'est cacahu├Ętes!"

In the evening, we took a taxi to a hotel restaurant overlooking the floodlit citadel. "Bon appetite," said the driver, dropping us off. The dining room was crowded with a package tour. Barb, after tasting her rose, said: "It starts out with great promise but in the end disappoints."

"Sounds like my prom night," said Dan.

A day of locks. They had moved from an education to an annoyance to a kind of welcome interlude. They gave us something to do. I started talking to the keepers. One told me that there was more traffic this year than in any since 2001. We had assumed the real crowds come in July and August, but he said no, as the prices go up then. It was June, so we were probably at the height of the season.

A middle-age woman said not all lockkeepers live in the lockkeeper's house; sometimes it's a family that agrees to care for the grounds, or run a little store. (A number of the locks sold regional products such as honey, jam, wine.) She had lived in this house -- the standard tan two-story with pale green shutters -- for 21 years, though had worked on the locks for 30 altogether.

"Ask her if anyone's ever fallen into the canal," Dan said.

"In 30 years," she said, "I've seen maybe two people fall in."

Farther down, a lockkeeper stood talking to a friend, who noted the name on our boat.

"Lully," he said. "He was a composer, I think, during the time of Louis XIV."

We docked for the night next to a field. There were no other boats. The week's first rain started falling, so we ate inside: Barb's delicious veal stew. Then, with the rain tapping the windows, Dan brought out his harmonica. Donnette lit a candle. We sang around the campfire. Folk, rock, Beatles; even world music: Milord, Kalinka, Guantanamera, Molly Malone; Hania threw in a few Polish songs. I wondered if younger generations will have this reserve of (mostly) shared melodies, or if, in situations like this, they'll just sit around and listen to their iPods. We sang late into the night, as if we were the only people in the world.

In Castelnaudary we docked in front of the police station and went our separate ways for lunch. In the afternoon we climbed our last lock and drifted into Le Segala. A row of two-story houses faced the canal, anchored at the far end by a restaurant-cafe. Exploring, we found that this was pretty much the town, with the exception of the tile factory behind the facade. We cleaned the boat and headed to the restaurant for dinner.

The patronne was an unsmiling, heavy-set woman who spoke decent English. I had the worst meal of the trip -- tough frog's legs and even tougher steak -- but the setting was lovely, and the darker it became, the lovelier it got. The outdoor tables filled slowly. A small band, synthesizer and accordion, played softly. Our last night on the Canal du Midi.

The crew of the barge that had been following us -- the three floozies and their captain -- made an appropriately late appearance and we all smiled at each other like old but distant friends. Two little girls in summer dresses chased paper airplanes while their untroubled parents smoked and talked. A South African couple, the man in a straw hat, danced a tango. Then the patronne grabbed one of the floozies -- her face red from the sun -- and they danced between the tables and out into the street. It was like watching a Piaf song come to life.