Route number is E21. Remember it—the number stays the same everywhere: on the stop display, in apps, on the vehicle itself. Look for E21 specifically. If you're not sure you found the right stop, just ask someone nearby: 'Does bus E21 stop here?'

This route serves the San Sebastián (Spain) region. In larger metro areas, routes can pass through several districts or towns. To know for sure if it works for you, pull up the route map and check the key stops and direction.

Starting point is Hondarribia. Usually at the first stop there's a turnaround or layover space where drivers rest between runs. If you want to guarantee a seat, get on here—the vehicle is just starting out and still mostly empty.

Final stop is Donostia. Everyone gets off here, the vehicle turns around and heads back after a few minutes. Missed your stop? No big deal—just ride to the end and come back on the same route.

Operator is Ekialdebus S.L.. This is the official company responsible for the route. If you run into problems (rude driver, breakdown, dirty vehicle, delays)—contact them. It helps to note the time, direction, and route number—makes your complaint more specific and gets handled faster. Contact info is usually on the company website or in transit apps.