We did this over the summer, and I've been meaning to come back and post about it. I found it a bit hard to cobble together information about the trip online, and so thought it might be helpful to some to just have it all in one place. Hopefully, it's all still up to date.

The stretch of the Danube between Melk and Krems is spectacular. There are two boats that do the trip every day in the summer – one is a company called DDSG and one is a company called Brandner. Once you plan the river journey, the rest of the day sorts itself out. The Brandner ship leaves Melk around 1:45 and the DDSG ship leaves Melk around 1:50.

You can go in the opposite direction – from Krems to Melk – but it takes twice as long, because the current is strong on the Danube.

The classic way to do the day trip is to leave Vienna early in the morning by train to Melk. Visit the famous abbey in Melk, for a couple of hours, have lunch on the beautiful old main drag in Melk, then take the cruise on either the 1:45 or 1:50 boat to Krems, and then take the train back to Vienna.

Here are some tips.

1. By far, the most economical way to do it is to buy a “combi” ticket at the train station in Vienna. For 50 euros, you get a ticket to Melk, a voucher to tour the abbey, a voucher to take the boat, and a return train ticket from Krems. There appeared to be some places on line to buy the ticket, but pickup directions were unclear. Also, if you have under 18s, you actually get a discount by purchasing at the station. Leave yourself a bit of extra time in the morning to get the ticket, because you need to actually buy it at the ticket office instead of the machines. (The machines actually showed the ticket, but we couldn't purchase it even though we had no trouble purchasing other tickets using the machines.) We left around 8:30 and arrived at Melk around 9:30. Trains leave frequently from the main train station – Wien Hbf. You connect in St. Polten. It’s an easy connection, but it’s tight. Don’t try to use the bathroom between trains. There is one nonstop train per morning most mornings from the western station in Vienna – Wien Westbahnhof – but that station is a bit out of the way.

2. The walk to the abbey from the train station is pretty obvious -- it's straight up the hill and takes 10 to 15 minutes. There is a guided tour, and for some times of the year (off season) you must take the tour to see the abbey. The timing of the tour was pretty convenient, but it's actually not really worth it even though it's only a couple of euros. There’s a museum and the abbey itself and the tour spends way too long in the museum.

3. To get to the boat docks, you walk down the hill into the old part of town and head toward the river. We had time for lunch and ate at Rahauskeller Melk, which is right in the pedestrian part of the town. Really good restaurant -- hearty standard food, not fancy, decent prices, outdoor tables, good service. To get to the boat docks, you continue through town to the river and then take a right on Linzerstrasse and head along the river. As you approach a parking area, there is a path to the left that forks off from the road and continues down along the river -- walk down that until you see the kiosks where you exchange your combi voucher for the boat ticket. There are some other docks on the other side of the river, but these, as I understand it, are for the long cruises like Viking and other riverboats, not the day cruises. From the abbey to the docks was about 20 minutes at a reasonable pace.

4. You can take either boat, the docks are right next to each other. You exchange your voucher for a ticket for the boat. I don’t think there’s a major difference between the two – we took the DDSG though the other one looked a little nicer.

5. When you get off in Krems, it’s a fairly long walk to the train station and there is not all that much to see in Krems. Alternatively, you can get off the boat in Durnstein. That’s what we did. Durnstein is tiny, but it’s spectacular – it’s like a postcard. And the "town," such as it is, is right near the boat dock. The problem with going to Durnstein is that you can’t get a train from there back to Vienna. Instead, what you have to do is take a bus from Durnstein to Krems. It’s the WL1 bus and it leaves from the outskirts of Durnstein and goes directly to the train station. It’s timed to get there a few minutes before the train to Vienna leaves from Krems. Or you can just take a cab. You can pay directly on the bus. The directions from the boat dock to the bus are a bit complicated, but it's fairly easy when you're there. We don't have much German, but "autobus nach Krems?" got us pointed in the right direction. It leaves every hour, so know the timetable before you go.

6. The trains from Krems go to a different station in Vienna – Franz-Josefs station. It’s not a very convenient station. Instead, we got off the train one stop before Franz-Josefs at Spittelau, which is a Vienna u-bahn station and is easily connected to the rest of the city. It was simple to get back to our hotel from Spittelau.