The Three Gorges Dam on China’s Yangtze River was so huge it actually altered the Earth’s rotation. Containing around 44 billion tons of water, this dam is the largest in the world. To match the scale of this project, China needed to make infrastructure that was equally massive, including an elevator that can lift entire ships.

Resembling a huge, windowless building, this elevator is capable of hoisting vessels that weigh up to 3,000 metric tons straight up the side of the dam. Of course, 3,000 tons is modest compared to some of the biggest ships the world has ever seen, but it’s still impressive the elevator can hoist this size ship 370 feet up.

This ship lift has been operational for about a decade, carrying over a million passengers and 15 million tonnes of cargo as of February 2024. It was created because the dam, while generating huge amounts of power, essentially ended up acting as a 175-meter-tall barrier along the Yangtze, which is China’s longest river. Much like the Panama Canal, the Three Gorges Dam did operate a system of five-stage locks that allowed ships to climb like a staircase through the dam to pass through one of the country’s most important waterways. However, it took ships nearly three hours to get through. The lift slashed that down to roughly 40 minutes. 

Building something this huge was no easy feat. The original plan was approved way back in 1992, which was around the same time the construction of the broader Three Gorges project itself kicked off. Initially, the idea was to use steel cables to suspend the lift chamber, but that was scrapped because of concerns about instability. Then, in 2003, a German engineering firm called Krebs and Kiefer came up with something different that used the Archimedes’ principle. 

This is the same science that explains how massive Navy ships actually float despite their weight. The basic idea is that if you have a chamber full of water and you drop a ship in, the ship pushes out water equal to its own weight. In this case, concrete counterweights suspended from cables are pushed down into the water, displacing the water and lifting this elevator.

Then, four gear-driven mechanisms arranged symmetrically around the chamber lock the ship in place at four support points. Those prevent the water inside from tilting or sloshing around, which is important to prevent imbalances. Additionally, there are also damping systems in place to absorb any seismic forces. As highlighted by the Global Times, they work by transferring any excess energy into the tower columns, which prevents the chamber from dropping. This basically makes the elevator resistant to earthquakes.