Bilboa bus station

I have no personal knowledge of the situation, but this relatively recent TripAdvisor thread indicates there may be a problem: https://www.tripadvisor.com/ShowTopic-g187454-i517-k11794215-LeftLuggageatBilbaoTermibus-BilbaoProvinceofVizcayaBasque_Country.html

However, there is a commercial operation that offers several different locations in the city: https://bagbnb.com/luggage-storage/bilbao . So it appears there's a back-up plan available to you if the bus station option doesn't work out.

I have stored luggage in a variety of places in Europe and Morocco, using lockers, staffed counters, my hotel, etc. I've never hesitated to do it and I've never had a problem. I do, however, keep a small lock on my suitcase. It would be easily broken, but that would be immediately obvious, so it's unlikely anyone would consider it worth the risk. Also, it is not an expensive suitcase, and I don't wear expensive clothing. When I am planning to leave my bag somewhere, I make sure my tablet computer and any excess cash I have are either buried in my purse or in a money belt, but that's what I do during bus and train rides as well.

In case you are not aware of it, the Casco Viejo (historic district) in Bilbao is larger than the one in San Sebastian, and much less touristy.

For a short stay, there are lockers at the bus station. As of last September, they were available at the temporary ticket office, in use during construction in the main station.

Thank you so much! I will look into all your suggestions!