Three Rivers (Dreiflüsse) Sightseeing Boat Cruise
Passau is THE City of Three Rivers, and this ~45-minute cruise is the only way to actually see the famous confluence from the water — where the blue-green Danube, the milky alpine-green Inn, and the dark Ilz meet and run side-by-side in distinct colors before mixing. You glide past the Old Town's Italianate skyline, the Veste Oberhaus fortress on its bluff, and the Mariahilf pilgrimage church. It is the single signature image first-timers come for, and the boat docks right where river-cruise ships tie up, so there is zero transfer.