El Castillo and other caves in N Spain - tour guides?

When my kids were little we visited the Covalanas Cave. I was impressed by the way the animals were made with fingerprints.

All caves in the Cantabria and Asturias regions have to be visited with a previous booking and the visit can only be done with a guide that works at the caves. You cannot visit it without the cave guide specific for that cave. If you want to visit El Castillo (and I would combine it with Las Monedas, just a fifteen minute walk away and same place for tickets), for a guide in English you have to write them and ask for a private visit in English. The cost is 90eur per cave, as it costs the same as for a full group in Spanish (9 persons).

https://cuevas.culturadecantabria.com/en/

I have visited different caves in Spain and France. I have never taken an English tour. When the guides knew that I was linguistically challenged they were very helpful. I have "survival" French and Spanish. Some research prior to the visit will be helpful even with an English tour.
Brad

I don’t understand how you toured the caves with a private tour guide.

Regardless, Tito Bustillo was our favorite of the 3 we saw in northern Spain (el Castillo and Altamira were the other 2).

If this is your thing I found Niaux in France to be my favorite. Kind of by a long shot. I’ve been there twice and to the Dordogne caves twice.

I was going to mention Niaux, but Matt beat me to it. We were there many years ago (20?); but even then, reservations were required. There were very limited numbers of tours in English. Of all the caves we have visited, I feel that it is the least modernized. No lights - - each pair of visitors carries a lantern, and the guide uses a laser light. No paving - - not for those with mobility challenges. Perhaps things have changed since we were there, but I loved that very special experience.oo