How does the ship travel from the lower reaches of the Three Gorges to the upper reaches?

The ship enters the upstream from the downstream: 1. Open the downstream gate, close the upstream gate, make the water level in the lock chamber consistent with the downstream water level, and the ship enters the lock chamber. 2. Close the downstream gate, open the upstream gate, make the water level in the lock chamber consistent with the upstream water level, and the ship enters the upstream.

In fact, this is the opposite of the boat moving from upstream to downstream. If you don’t understand, you can watch the video, the animation demonstration will make it easier to understand.