From San Sebastián · 43.32° N · 1.98° W
Five days from Maundy Thursday to Easter Monday: processions and Atapuerca in Burgos, Gregorian chant in Silos, Lapurdi in spring and plans near home for rainy days.
Map
In Holy Week Burgos has processions through the historic centre, around the cathedral, and the Atapuerca sites open with guided visits. Book the visit and meals by phone. Easter Monday is not a holiday in Castilla y León: Las Huelgas and many museums close that day.
The monks of Silos sing vespers every afternoon, and in Holy Week the monastery church fills: arrive in good time. Half an hour away, Covarrubias and its olla podrida. April opens the good season in the Arlanza valley, with the juniper woods green.

Holy Week coincides with the return of the La Rhune train, which reopens at the end of March, and the cliff boat, which starts in April. In France Easter Monday is also a holiday: that day Saint-Jean-de-Luz fills, so go up La Rhune on Thursday or Friday.

It works in any weather, because the old town and the harbour do not close. From April the Maison Louis XIV, where the king stayed for his wedding, also opens inside. Half an hour from home, it is the plan for a Holy Week day that dawns with rain.

If Holy Week turns wet, the Biarritz aquarium is the refuge: it opens almost every day and has seals, sharks and a pushchair-friendly route. Easter Monday is a holiday in France and there are more families: go first thing and buy the ticket online.

The Balenciaga museum, under cover, is half the plan and works just the same with rain; with sun, the Ratón de Getaria and the walk to Zarautz. Outside July and August the museum is closed on Mondays: do not leave it for Easter Monday. Kaia Kaipe is closed on Tuesdays.

In spring the Rioja Alavesa vineyard sprouts and the countryside is green around the wall. An hour and three quarters by car and back for dinner. Amelibia is closed Tuesday and Wednesday; on Maundy Thursday and Good Friday, with half of Spain on holiday, book lunch.
Questions
Maundy Thursday, Good Friday and Easter Monday. With Saturday and Sunday, that is five days in a row.
In Burgos, about two and a half hours away, with processions through the historic centre.
It is a holiday there too, so the coast fills. Tourist trains and boats operate, but many shops close.
Alternate the coast's indoor plans, such as the Biarritz aquarium and the Balenciaga museum, with a getaway inland, which is drier.
Geocaliahttps://www.geocalia.com/en/spain/basque-country/san-sebastian/getaways/easter-holy-week