Link: https://visdeurbel.nl/en/

Did you spot a fish? Press the Fish Doorbell! Then our lock keeper can let the fish through.

Wait, are they crowd sourcing the training data gathering of a fish recognition vision model? Genius

That site is incredibly satisfying to scroll through. Poke around, it's really cool

And op, thanks for posting! It's really awesome

Why do they leave the lock closed? Why not just let the fish swim through?

While there are many different types of fish to be found in the canals, there are relatively few safe places for them to shelter. This is especially relevant during the breeding season in the spring, during which they tend to migrate to larger bodies of water, like the Kromme Rijn southeast of the city. However, their journey might be interrupted by a sluice gate, preventing water from overflowing the city's canals. If the sluice gate is not automated and a sluice keeper is not present to open the gate for the fish, they are unable to continue their journey. Enter the fish doorbell.

https://www.atlasobscura.com/places/weerdsluis