[rmc]

> “The "Navigable by canoe" filter seems to filter out everything”

The data is 100% from OpenStreetMap. That map only looks at things with the `canoe` tag in OSM. There are a lot of waterways in OSM which do not have this tag. If you know of missing data, you can just edit OSM and it'll show up on WWM.org tomorrow!

(I made WaterwayMap.org)