travel from santiago to porto airport?

Alsa have buses from Santiago bus station to Porto Airport - I got it in 2012 and it's a very comfortable way of getting there. Check the website alsa.es and go to international, and remember Porto is Oporto.

In March trains south were later and at different times on Sunday. Check schedules carefully.

Train

Renfe train from Santiago to Vigo;

Renfe train from Vigo to Valenca;

CP Regional train from Valenca to Porto Estação de Campanhã; and,

Porto Metro from Porto Estação de Campanhã to Porto Airport.

OR

Renfe train from Santiago to Vigo;

CP Celta train from Vigo to Porto Estação de Campanhã; and,

Porto Metro from Porto Estação de Campanhã to Porto Airport.

OR

Bus

Monbus from Santiago bus station to Vigo bus station; and,

Autna bus from Vigo bus station to Porto Airport.

Renfe
http://www.renfe.com/index.html

Comboios Portugal (CP)
http://www.cp.pt/cp/displayPage.do?vgnextoid=87cbd5abe2a74010VgnVCM1000007b01a8c0RCRD

Estacion de Autobuses Santiago
http://www.tussa.org/web/interior.php?txt=arbore_web5&lg=cas

Vigo Bus Station
http://vigobus.com/

Monbus
http://www.monbus.es/index2.htm

Autna
http://www.autna.com/es/

3002 Porto Airport

ANA manages Porto Airport (OPO)
http://www.ana.pt/en-US/Pages/Homepage.aspx

3003 Porto Metro

Travel from Porto Airport (OPO) to CP trains at Estação de Campanhã by Metro. Take Metro line E from the Airport to Estação de Campanhã.

Metro do Porto
http://www.metrodoporto.pt/