It's smart to book well in advance, of course. But if you failed to make a reservation, there are options for the adventurous traveler. Due to last-minute cancellations, a handful of comfortable rooms for a single overnight stay can be found. Almost any bartender on the main square can lead you to a local or an American expat who has procured large apartments for the Festival. Another option is to stay in the beachside resort town of San Sebastian.
Buses leave from downtown terminals in each city.
San Sebastian has several tourist offices that can be reached on foot. The offices can often help with obtaining last-minute rooms. The bus schedule is beefed up during the festival. If you're really desperate, Pamplona allows overnight camping in the town's main park. Reservations are neither necessary nor possible.