The LF9 "water level" bike route follows the NAP gradient four hundred km across the Netherlands. Here's a 55km timelapse from Nijkerk to Utrecht Centraal, with only a few meters of elevation change https://youtu.be/PAmJl1RaGGQ
Follow
Some highlights are
[Spakenburg harbor](https://www.youtube.com/watch?v=PAmJl1RaGGQ&t=168s), [Kasteel Groenveld](https://www.youtube.com/watch?v=PAmJl1RaGGQ&t=493s), [waiting for a drawbridge](https://www.youtube.com/watch?v=PAmJl1RaGGQ&t=1065s), and [Utrecht's massive bike parking](https://www.youtube.com/watch?v=PAmJl1RaGGQ&t=1148s)
