This route connects the North Sea (town of Husum) with the Baltic Sea (town of Eckernförde) along the ancient Danish fortification walls known as the Danevirke (500 CE). It is flat and easily runnable and makes for good wide views over the state of Schleswig-Holstein’s plains. You can run either direction.
Great idea for a C2C-route here in Schleswig-Holstein and congratulations for your "First Known Time"!
I did a almost the same coast to coast crossing one year ago (https://www.strava.com/activities/2934827295) and as soon as I'm back in to longer distances I might aproach this route!