San Sebastian (San Sebastián) or Donostia is a coastal city and municipality located in the Basque Autonomous Community, Spain. It lies on the coast of the Bay of Biscay, 20 km (12 miles) from the French border. The capital city of Gipuzkoa, the municipality's population is 186,095 as of 2015, with its metropolitan area reaching 436,500 in 2010. Locals call themselves donostiarra (singular), both in Spanish and Basque. The main economic activities are commerce and tourism, and it is one of the most famous tourist destinations in Spain. Despite the city's small size, events such as the San Sebastián International Film Festival have given it an international dimension. San Sebastián, along with Wrocław, Poland, was the European Capital of Culture in 2016.

The city is located in the north of the Basque Autonomous Community, on the southern coast of the Bay of Biscay. San Sebastián's three beaches, Concha, Ondarreta, and Zurriola, make it a popular resort. The town is surrounded by easily accessible hilly areas: Urgull (adjacent to the old part of the city), Mount Ulia (extending east to Pasaia), Mount Adarra (south of the city) and Igeldo (overlooking Concha Bay from the west). The city sits at the mouth of the River Urumea, Donostia was built to a large extent on the river's wetlands over the last two centuries. In fact, the city centre and the districts of Amara Berri and Riberas de Loiola lie on the former bed of the river, which was diverted to its current canalized course in the first half of the 20th century.

San Sebastiаn main economic activities are commerce and tourism. San Sebastiаn is one of the most famous tourist destinations in Spain.
The international technology organisation Ikusi is based in San Sebastiаn. San Sebastián Airport (IATA: EAS, ICAO: LESO) is the airport serving San Sebastián in Basque Country, Spain. Despite its name, the facilities are located in the municipality of Hondarribia, with the runway stretching like a spit of land along the river Bidasoa right on the Spanish-French border. The city is served by Euskotren Trena, the main Basque rail operator. Euskotren Trena operates trains to Bilbao and other destinations, as well as the Metro Donostialdea and Cercanías San Sebastián within the San Sebastián metropolitan area. There are frequent trains to Hendaye in France, which is connected to the French rail network. The city is also served by San Sebastián Airport in the nearby municipality of Hondarribia. San Sebastián Airport currently has no international destinations. Biarritz Airport in France is located about 50 km from San Sebastian.