Pasaia (Spanish: Pasajes) 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 birthplace of the famous admiral Blas de Lezo and of the fashion designer Paco Rabanne.

Pasaia lies approximately 5 kilometres (3.1 mi) east of Donostia's centre, lying at the foot of Mount Ulia and the Jaizkibel massif. The municipality numbers 16,056 inhabitants (as of 2008^[update] 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.

The first documented mention of this place, written in 1203, calls it Oiarso. The name was later changed to "Pasage" (first attested in the 15th century), which means 'port' in Gascon. Gascons had come to inhabit the area side by side with the Basque people at the beginning of the 13th century.

It was a major source of revenue for the municipal coffers on the strength of its position on commercial sea routes. The Guipuzcoana Company used this as its main port, and there were as many as seven shipyards here in the mid-17th century. Historically the area was controlled by two competing baronies: Hondarribia, controlling Donibane, the right bank; and Donostia (San Sebastián), with jurisdiction over San Pedro, the left bank. Donibane separated from Hondarribia in 1770, and San Pedro separated from Donostia in 1805.

The district of Antxo was formed in 1890, when the Irun-Madrid railway came through. Trintxerpe, next to San Pedro, was the last district to form. Trintxerpe and Antxo eventually became a continuous urban strip with the eastern districts of Donostia.