Eurailpasses and German Rail Passes are honored by KD Rhine Line on the Rhine River and on the Mosel River between Trier and Koblenz. (If you use the fast hydrofoil, a supplementary fee is required.) The rail lines follow the Rhine and Mosel rivers most of their length, meaning you can go one way by ship and return by train. Cruises generally operate between April and October. If you are planning to visit Denmark or Sweden after Germany, note that Scandlines ferries offer discounts for Eurailpass owners.
KD Rhine Line. 0221/208–8318; www.k-d.com.
Scandlines. 0381/54350; www.scandlines.de.