Pirna is a good place to hop on your bicycle, either to get there and back, or to move around. Most of the town is located down in the Elbe river valley, and even the hills around the town are not *that* steep. A really enjoyable way to get there is a bike trip along the river; the Elbe cycling trail is one of the favourites in Germany.
Locals use their bicycles to get around, too. Many ride it to get to the train station - in summer as well as in winter! - which is a bit outside the old town. See pictures!
Getting TO Pirna by bus is not really an option. Train is more efficient. But for getting AROUND in Pirna, its suburbs and the region Saxon Switzerland bus is the way to go. The central bus station is right next to the train station (see pic, train station in the background). There is another bus stop a few metres from the old town called "Breite Straße" where most buses stop also.
The buses are included in the VVO regional transportation network, thus the same fares as for trains apply. In 2011 a single ticket in the zone Pirna is (was) 2 Euro.
The buses run frequently during the day. Expect less buses on weekends than on weekdays except for the touristy routes. As you can see on the picture some buses also have carriages for bikes. Particularly popular for bike rides is the bus to Rosenthal right by the Czech border, which is at quite high elevation. Other important bus routes are 241 (via Königstein Fortress and Bad Schandau to Kirnitzschtal / National Park and Hinterhermsdorf) and 237 to Bastei viewing point.
To get to Pirna by steam-ship from Dresden takes a lot more time than by train or car, BUT it is also more romantic and you will pass by many interesting places on your way to Bad Schandau, that you could explore afterwards by car.
For timetables and more infos , just click on my link below - these ships run regularily even at certain times in winter !
I did such a cruise to Bad Schandau first and it took the whole day.
If your time is rather short it might be the best to skip the cruise back and take the train in order to save some time.
Probably the most pleasant and relaxing mode of transportation to get to Pirna is by steamboat. These antique paddle steamers run on the Elbe river from downtown Dresden via Pirna to Bad Schandau in the National Park Saxon Switzerland close to the Czech border. It's not necessarily the fastest way to get to Pirna, but if you have a little more time and want to travel in a more relaxed mode then this would be a great option.
See the website for details on schedules and fares. Steamboats do not run in winter but quite frequently in summer. A plus is that you get a sort of "city tour" of Dresden with beautiful scenery, pass some sights like the Blue Wonder bridge and Pillnitz Palace.
The steamboat landing in Pirna is right by the old town, even closer to the heart of the city than the train station.
Sometimes a pretty smart way to get to Pirna's old town (especially if you arrive from Dresden-Pillnitz or from somewhere else north of Pirna) is to park your car across the river in Pirna-Copitz and take the ferry to the old town. Parking is free by the river in Copitz (unlike in/around the old town) and the cost for the ferry is not *that* much.
The ferry runs very frequently during the day, stops at sometime in the evening. If all else fails you can walk across the bridge - just a ten minutes walk from the old town.
It is very convenient to get to Pirna by Suburban Railway (S1 and S2) from Dresden. The trains run about every 15 minutes till late evening, and even during the night there are trains at least every hour from Dresden Hbf to Pirna and back.
S1 runs Meissen - Dresden - Pirna - Schöna (National Park Saxon Switzerland). S2 runs Dresden Airport - Dresden Hbf - Pirna. Since Pirna is located inside the VVO regional transportation network the fares and rules of the VVO apply. The zone 'Pirna' borders to the zone 'Dresden' e.g. which means you must buy a ticket for these two zones if you want to get from one to another (4 Euro in 2011).
Although it is located on the route Dresden - Prague, international trains do not stop in Pirna. You need to get off these trains in either Dresden or Bad Schandau and take the Suburban railway from there to Pirna.
The train station is actually a good 5 to 10 minutes walk outside the old town. The first train station from 1848 (next to the city museum) still exists but in 1874 the station was moved farther because of more traffic which needed more ground. That building from 1874 still serves as train station (modified, of course) and was recently renovated. It is small but has a ticket office, a small shop and a restaurant. The central bus station is around the corner so changing from bus to train or vice versa is quite convenient.
The train needs only about 23 minutes from Dresden and trains run several times each hour and will take you directely into the centre of Pirna !
It certainly makes sense, when you plan to take a cruise from Dresden to Bad Schandau to go at least one way by train in order to save time !
The ship takes more than 3 hours one way and I made the mistake to buy a return-ticket for the ship instead of taking the train back.
On the link below you may check the time-table for the trains !
On my picture : Schloß Sonnenstein, high above Pirna - a castle that was used as a nursing-home for mentally sick persons since 1811.
The Nazis killed 13720 people there as they regarded them "not worth living"
By car you may get to Pirna within a really short time from Dresden and it is the best to park your car at the river Elbe.
From there you may walk to the centre of Pirna within 3 minutes and the parking was even free of charge, when I remember that correctely.
On my picture you may see how really narrow the river is here, BUT be carefull in times of the floods, as the water-level was more than 2,5 meters above that in summer 2002 !!
Inside of Pirna a parking is hard to find and mostly restricted to local people !!