Knud Knudsen is barefoot, wearing shorts and has a mailbag on his back. He carries the mail along the same route each time — from the island of Pellworm in the North Sea to the islet of Süderoog. Only one family lives there, and they need to get their letters and packages on time.

"Just no refrigerators," says Knudsen — those have to come by boat. The regular hike across the mudflats is more than just a job for the 69-year-old postman; it's pure bliss. "I enjoy this peace!" he says. 

It' a nearly 7-kilometer (about 4-mile) walk to get there. After a short coffee break, he heads back again, timed with the rolling tides. He always has a few tourists with him in tow during the summer.

DW reporter Axel Rowohlt followed Knudsen, probably the world's only mud flat mailman.