Pasaia (Pasajes in Spanish) is a town and municipality located in the province of Gipuzkoa in the Basque Autonomous Community of northern Spain. It is a fishing community, commercial port and the birth place of the fighting admiral Blas de Lezo. Pasaia lies approximately 5 km east of Donostia's centre, lying at the feet of Mount Ulia and the Jaizkibel massif. The municipality numbers 16,056 inhabitants (2008 estimates), clustering around the Bay of Pasaia in four nuclei, namely Pasai San Pedro, Pasai San Juan (or Donibane in Basque), Antxo and Trintxerpe, with each part showing distinctive features.

Pasaia is mentioned in documentary records for the first time in 1203 as Oiarso. The name of the village was later changed to "Pasage", which means 'port' in Gascon. The Gascons had come to inhabit the area side by side with the Basque people at the beginning of the XIII^th century. The current name is first attested in the 15th century, when it was called the above "Pasage". In 1770 the district of Donibane received municipal rights from Charles IV of Spain.

Historically the area was controlled by two competing baronies, that of Hondarribia, who controlled the Donibane district, and Donostia, who controlled the San Pedro district. Donibane was detached from the Hondarribia barony in 1770, while San Pedro was separated from the Donostia barony in 1805. The Antxo district was formed in 1890, when the Irun-Madrid railway came through. Trintxerpe, next to San Pedro, was the last district to be formed. Trintxerpe and Antxo actually form a continuous urban strip with the eastern districts of the city of Donostia.