Uniworld Boutique River Cruises is offering savings of up to 50% and no solo supplements on selected rail journeys in September and October.
The three-night Venice & the Swiss Alps itinerary on the Golden Eagle Danube Express is available, with prices starting at £2,995 based on a September 6 departure.
Passengers will travel from Zurich to Venice, stopping at Ljubljana and Vaduz and visiting Lake Zurich and Lake Bled.
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Also featuring travel on the Golden Eagle Danube Express is the three-night round-trip Castles of Transylvania itinerary departing from Budapest.
Passengers will visit Sibiu, take a walking tour of Sighișoara and visit Bran Castle.
Prices lead in at £2,995 based on an October 10 departure.
All itineraries include return flights, accommodation, onboard dining, drinks, transfers and one-night pre-train hotel stay.
UK managing director Chris Townson said: “We are excited to share these incredible offers with our trade partners for September and October, with much more to come into 2024.
“Much like our river cruise offering, the Golden Eagle Danube Express journeys are truly once-in-a-lifetime and offer luxury accommodation and fine dining as well as a host of stunning views and immersive stops throughout their varied destinations.”