Hi, I gather it's a village location, do you know if there are any restaurants, bar, shops in the village?
Serdio is certainly not big, I have driven through there before, but don't remember there being any shops or restaurants, and I couldn't find anything online. Your only possibility is that there is a Posada (like B&B) in the village which might do evening meals, and there might be a bar. There are plenty of shops in Unquera and San Vicente though, as well as restaurants, and in Pechon nearby also. Sorry that's not very specific, but hope it helps a bit!
We stayed in Serdio in awful self-catering accommodation (Casa Los Emboscados) through Brittany Ferries in May/June 2012.
Serdio itself is probably the least friendly place we have stayed in recent times. The locals seem to go out of their way to look disapproving and unfriendly. Our next door neighbours seemed to be running a noisy motorcycle and car repair business, and there is almost always at least one dog barking - day and night!
We would not stay in Serdio again, and there isn't really anything to go there for otherwise.
I stayed in Serdio, also in Casa Los Emboscados. I was there with my wife and young daughter. Honestly, I absolutely loved every minute. The house itself was charming, well equiped, with more than enough space. This was clearly somebody's home or weekend home. They are not professional holiday letters. I found that the locals were very friendly (didnt really speak any English, but that's ok!) I would urge anybody planning a tourist style holiday not to bother. This is a small agricultural village, close to St Vicente de la Barquera, Camillos, Santander, and most importantly the Picos de Europas. There is not much going on in the village of Serdio, but if you just want to kick back, and enjoy some wine, cook great food and use it as a base to explore the mind boggling regions of Cantabria and Asturias, this place is a dream. I certainly dont recognise the problems described above. The car repair shop was pretty quiet most of the time, and isnt even a next door neighbour. It was in fact about 150 meters up a road, not exactly opposite, but nearly opposite the house. In fact, the only cars I saw were the occassional ones on the road which passed the house about once every 20 minutes! There were often cows and horses going past, as well as the occassional hiker. As for the dog barking - there was certainly some, but it was by no means a problem and was certainly not day and night. Whilst I accept that everybody has a different view, and sometimes one can be lucky or unlucky, I can only reccomend the place based on my visit. But be warned, you need a car, you need to be willing to move around, and you need to know that there is nothing in Serdio other than two little bars. It is an agricultural village and you will be the only tourist if you go. You could say it is the real Spain.
We have just returned from Casa de los emboscados and agree with the previous comments. We went to the bar almost every night and were made very welcome by all. The bar was particularly lively at weekends and there were bbqs and live music. The owners of the house couldn't have been friendlier and went and bought us a bbq when I expressed disappointment that there wasn't one. We used the pool and the gym and the house although quite rustic,was very well equipped and comfortable. No problems with motorbikes and although there were dogs(which you'd expect in rural Spain),they did not bark day and night! I was very worried when I read the first comment before we went and am pleased and relieved to report that this description is totally inaccurate!