A concrete wall more than two kilometres long blocks the Yangtze between two mountains in Hubei. River cruises linking Chongqing and Yichang almost all stop at Sandouping, the town where the Three Gorges Dam is anchored. After days of cliffs, mist and perched temples, the call abruptly changes register: here stands the world's largest hydroelectric power station, set across the current like a border. You don't come here looking for an old city or a beach. You come to measure what humans have dared to do with one of the planet's great rivers.

Crossing the dam on board

Passing the dam is already a highlight of the voyage. Large vessels use a five-step water staircase with two lanes, and the full transit takes about four hours. Many cruises schedule it for the evening: the lock walls close, the water rises or falls with a deep rumble, and passengers follow the manoeuvre from the outer decks. Lighter vessels, under 3,000 tonnes, have a quicker option: a ship lift, the largest in the world, which raises the hull and its basin of water in about forty minutes. Either way, you long remember the moment an entire ship climbed a hill.

Tanziling Hill

The shore excursion leads to Tanziling Park, laid out on a height overlooking the entire site. Observation platforms equipped with telescopes offer the best view of the reservoir: on one side, the artificial lake stretching upstream; on the other, the lock staircase where convoys wait in line. On a clear day, you take in at a single glance the wall, the cranes, the high-voltage lines and the mountains framing it all. It's a strange feeling to see a thousand-year-old landscape reorganized by a twenty-first-century construction project.

Understanding what you're looking at

The site is visited with a guide, and the explanations help grasp the scale of the project: power generation, flood control and navigation opened to seagoing convoys all the way to Chongqing. Depending on the guide, the commentary also touches on the human cost of the reservoir, the towns and villages relocated that the river's elders still mention. The site doesn't try to move you. It lines up figures, models and viewpoints, and lets each visitor form their own opinion of this colossus.

Xiling Gorge in the background

Downstream of the site begins Xiling Gorge, the longest of the Yangtze's three gorges. Its wooded slopes and grey cliffs recall what the landscape must have looked like before the construction, and navigation returns to a more contemplative pace. Several itineraries combine the dam visit with this stretch, so the day swings from one extreme to the other: concrete in the morning, stone and greenery in the afternoon.

Port call highlights

As the ship gets under way again, many passengers stay leaning on the railing, gazing at the shrinking wall. Opinions often differ on board: a feat for some, a wound for others. That is precisely what makes the stop valuable. Few ports of call leave so much to reflect on about how a country transforms its territory, and the Yangtze, for its part, continues on its way to the sea as it always has.