Bakio is about a half hour’s drive from Bilbao, the biggest city in the Basque country of northern Spain.
It’s about four hour’s drive from Madrid to Bilbao, so four and a half hours from Madrid to Bakio.
There aren’t trains, though there is pretty good bus service.
Otherwise, you can fly into London/ Paris/ Amsterdam/ Frankfurt/ Madrid/ Barcelona/ etc. and take a flight to Bilbao.
The Bilbao airport is between Bilbao and Bakio and it’s an easy twenty minute drive.