by car:

Using the highway (Autobahn):
A3 Cologne – Frankfurt – Nuremberg – Passau – Linz – Vienna
A92/A3 Munich – Landshut – Deggendorf – Passau
On the A3, take the exit ‘Passau Mitte’ and, at the traffic lights, turn left in the direction of Passau. Follow the road for about one kilometre, then take the first exit right onto Pionierstrasse. Proceed along this road until you reach a T-junction, then turn left onto Neuburgerstrasse. Keep going straight along this street. After about 1.5 kilometres, when you reach the fifth set of traffic lights, turn right onto Leonhard-Paminger-Strasse and keep going until you reach the T-junction, where you should turn left onto Innstrasse. You will see the University buildings come up on your right and left as you continue along Innstrasse.
For more information on parking spaces and car parks, including Park & Ride car parks railway stations, bus lines and taxi stands, use the interactive map of Passau

Distances – Duration (conservative):
Munich 200 km – 2:00 h
Munich Airport 160 km – 1:30 h
Nuremberg 230 km – 2:20 h
Frankfurt 450 km – 4:20 h
Linz 80 km – 1:15 h
Vienna 300 km – 2:50 h
Prague 220 km – 3:05 h
Regensburg 125 km – 1:30 h

By train

Find your suitable train schedule here: https://www.bahn.de
Intercity (IC) trains:
Nuremberg – Passau – Vienna
Dortmund – Cologne – Frankfurt/Main – Würzburg – Nuremberg – Regensburg – Passau – Linz – Vienna – Budapest
Intercity Express (ICE) trains:
Ostend – Amsterdam – Brussels – Aachen – Frankfurt/Main – Würzburg – Nuremberg – Regensburg – Passau – Vienna
Hamburg – Hanover – Göttingen – Würzburg – Nuremberg – Passau – Vienna
Regional trains (RE):
Munich – Landshut – Plattling – Passau

by plane

From Munich airport:

Onward journey with door-to-door shuttle service:
(Recommended: Takes about 1,5 hours from the airport to the hotel.)
Book here in advance: http://www.flughafentransfer.at

Upon arrival at Munich airport, just follow the signs to the Rental Car Services (located in the Munich Airport Centre (MAC). Find the desk where the shuttle services are located opposite the escalator to the S-Bahn (local transit train), in between the service desks of the rental car services and Deutsche Bahn) and present yourself to the SMS (Salzbuger Mietwagen Service) representative at the desk.

Onward journey by train:
Go to the Munich Airport Centre located on Level 03 and purchase a ‘Bayern Ticket’, indicating the number of travellers on the ticket (up to 5 persons can travel on one ticket; the price depends on the number of persons indicated. Please make sure your name is written or printed on the ticket, as otherwise the ticket is void). Bayern Tickets are valid on weekdays from 9:00 a.m. until 3:00 a.m. the following day and can be used on all regional trains, suburban trains, the subway and most bus routes (but not on ICE or IC trains). On Saturdays and Sundays, Bayern Tickets are valid from midnight until 3:00 a.m. the following day.
Do not take a local train to Munich but rather bus no. 635 to Freising. The bus departs just outside the Munich Airport Centre (MAC) – follow the ‘Bus’ signs. The terminus of the bus service is Freising station; the trip will take some 20 minutes. At the station, take the Regionalexpress (RE) train to Passau. The train journey lasts about two hours and there is an hourly service. Passau is the terminus of the train. Please note that the Bayern Ticket is valid on buses and trains (but not ICE/IC trains) and can only be purchased before embarking upon the journey, either at a ticket machine or at the train counter.
The train ride from the Munich airport to Passau will take about 2,5 hours.

Onward journey by (rental) car:
via autobahn A92 Landshut – A3 Passau (about 1,5 hours)
find more information here: http://www.munich-airport.de

From Frankfurt/Main airport:

Onward journey by train: direct or via Hanau ICE train to Passau about 4,5 hours
Onward journey by car: via autobahn A3 to Passau

From Nuremberg airport:

Onward journey by train via Nuremberg city: direct ICE train to Passau about 2,5 hours
Onward journey by car: via autobahn A3 to Passau

From Linz airport:

Onward journey by train via Hörsching: direct train to Passau about 2 hours
Onward journey by car: via autobahn (toll road) A25/A8
Door-to-door shuttle service (book in advance) http://www.flughafentransfer.at/