Towns to visit west of Bilbao

For 3 days west of Bilbao, Llanes is a very good choice as it gives you access both to a very scenic stretch of coastline and to the Asturian side of Picos de Europa (Covadonga lake, Cares gorge). I have never stayed there, but I passed through, and I might actually stay there this summer (if I can convince my partner to travel by car from Paris to Asturias... rental car prices are still sky-high).

But if you only have 2 days, it is not worth going that far. I would head to Santillana del Mar and Comillas instead. Santillana is very touristy, but well-preserved, and Comillas is an interesting seaside town famous for a Gaudí-designed monument. Excellent beaches nearby at Suances and San Vicente de la Barquera, too.

Otherwise, closer still to Bilbao, Santander has an undeserved bad reputation. It is quite attractive beyond a facade of 1940s buildings, and there are great beaches and restaurants. No car needed, as a bonus - and an airport with flights to Ireland if the dates work!

I haven't been to Llanes.

Santillana del Mar is a touristy but very old town near the coast between Santander and Llanes. It's worth a stop for sure. Beyond Santillana del Mar is Comillas, a town with a few modernista buildings.

I don't recommend Santander itself unless you want to see another impressive beach. The city suffered a huge fire in the 1940s and lost most of its historic architecture. It's not a bad (or ugly) place, but I think there are much better options in that part of Spain.

Another possibility is the Picos de Europa area south of Llanes. It has very nice scenery (somewhat more dramatic than that of the Basque Country, though the latter is also good), including some Alpine lakes. The Fuente de lift takes you up to some high-mountain scenery. There's also the pilgrimage site at Covadonga. I thought the old stone town of Potes was really charming, though touristy. This might be a bridge too far from Bilbao, because I don't imagine you'd make good time on those roads.

I agree with Balso, Santillana del Mar would be a good choice, I was there a few years ago in August and while it was crowded during the mid day, most tourists were gone by late afternoon/evening. The town is very scenic and charming and there are also the nearby Altamira caves, the real caves are closed to the public but there is a really good full-scale replica cave that includes a guided tour and an outstanding Paleolithic museum onsite.

Another option I would recommend would be Potes, an atmospheric stone medieval town located high up in the Cantabrian Mountains, makes for a great base to explore and hike the stunning Picos de Europa National Park.

As a local from Bilbao, I´d recommend in Cantabria the town of Santillana del Mar as a nice place to stay (although touristy in weekends) and a good place to explore Santander (nice península of La Magdalena and "old" -1959- quarter, as it was destroyed by a fire in the fifties), Comillas and the prehistoric caves with rock paintings of Las Monedas, El Castillo, Covalanas,...really worth the visit. Ignore the replica of Altamira, more a museum than a cave and quite overrated, IMO. Somo and the towns on the opposite side of the bay of Santander and the spectacular beaches are a must. Also, the Sequoya forest near Comillas. Santoña, Castro Urdiales, Limpias...Llanes is also touristy, just entering Asturias but worth the visit (or the stay), as it´s the logical way to Potes (crowded in weekends too).

Thank you all very much for your great suggestions!

We enjoyed Comillas and Llanes, did not care for Santillana del Mar where we spent the night, over touristed and crowded..

I agree that Santillana Del Mar is very touristy during the day, but I takes on a completely different atmosphere during the evening when all the tourists depart. We stayed at Parador Santillana Gil Blas right on the main plaza the last time we visited there. Potes and Picos de Europa national park are a couple hours from Bilbao, while Covadonga and Cangas de Onis are about 3 hours away.

If you wanted to go south instead of west, there are a number of towns and places of interest less than 2 hours drive from Bilbao. Some include Vitoria-Gasteiz, Haro, Ermita de la Purísima Concepción (San Vicentejo), Ermita de Santa María de la Piscina, San Vicente de la Sonsierra, Briones, Monasterio de Santa María de la Piedad - Madres Dominicas, Laguardia, and Sajazarra.

I agree with the recommendation of the caves of Las Monedas and El Castillo, they are within walking distance of each other and both can be done in a morning or afternoon. I'd also suggest Potes, close to the above caves and the Picos de Europa.