Buses leave to most destinations in Turkey. A ticket to Diyarbakir costs 20 TL (09:00, 12:00 and 23:00, 6 hours), to Malatya costs 25 TL (08:30, 9 hours) and Trabzon costs 50 TL (07:30 and 12:00, 12 hours). Remember that most departure times are from the Otogar, a few km's out of town. Free shuttle buses run from the main ticket offices in the town centre but remember to be there at least half an hour before the scheduled departure time. As always, check details when buying the ticket.
Minibuses to Doğubeyazıt and Yuksekova for border crossings to Iran.
There are also two buses a day to and from Urmia in Iran costing only 15 Euros.
From Istanbul’s Haydarpaşa station (on the Asian side) there are trains direct to Tatvan, a town on the west side of Lake Van, two times a week, on Mondays and Fridays. This train (Vangölü Express) departs from Haydarpaşa at 10:55PM and calls in a number of cities and towns across Anatolia, including Eskişehir, Ankara, Kayseri, Sivas, and Malatya among others. According to the timetable all the way between Istanbul and Tatvan takes almost 40 hours (arriving in Tatvan at 2:17PM on Wednesdays and Sundays), frequent and probably long delays discluded. This is the longest (both in terms of miles traveled and time spent inside the train) non-international train journey in Turkey and gives a through panorama of almost all regions of inland Turkey. Inter Rail pass is accepted in this train. Once arrived in Tatvan, you can take the ferry which crosses the lake to Van.
International train from Istanbul to Tehran (Trans-Asia Express) calls in Van once per week (on Thursday evening, around 10pm, as of April 2011), see  (note that this link is not up-to-date as of April 2011, despite being the official website, the Van-Tabriz train leaves Van on Tuesday evening, not Wednesday)
Apart from Trans-Asia, there is also another international train service once a week (on Tuesday evening as of April 2011) between Van station and Tabriz in NW Iran.
There is an airport (Van Airport) located about 5-10 km away from the city. There are flights from Istanbul, Izmir, Ankara and Antalya. Outside the airport there are taxis to the city costing 20 YTL, but you can also walk for the main road where dolmuses stop and take you to the city only for 1 YTL. A new bus run by the municipality now serves the security entrance to the airport (past the taxis and towards the main road).
To get to the airport from the city centre, dolmuses marked Hava Alani leave nearby Hotel Akdamar (Kazim Karabekir Caddesi). Drive takes about 15 minutes, making weird detour becouse of the major roadworks.
There is a ferry line in the Lake Van, between Tatvan on the western shoreline and Van on the eastern shoreline. The ferry going to Tatvan was only at 9 or so PM. Maybe more in the summer?
It takes four hours to cross the lake.
The city is famous for its breakfast halls (kahvaltı salonu), in which for about 10 lira, you are served a really filling breakfast including locally produced cheese (different types) and honey among many other stuff. The price usually includes an unlimited amount of tea. Look around.
Plenty of hotels around the northern end of the bazaar.