I didn't rent a car... I wanted to be free to drink cañitas 😅 I never rented a car, in any vacation. But the trips I bought included transportation and for other (small) trips (like to various beaches) I took a taxi. Prices are acceptable... 5-20 EUR.
That is true. I don't know in other countries but in Spain we have very strict rules about not drinking when you're going to drive. I'm not sure if it's already in force, but the last update of that rule will/has lower/ed the limit so even one small beer would be beyond the limits of what's permitted.
Now I am on my way to visit volcanos and in weekend I'll visit a beach with black sand. Never saw one before. Its name is Marañuelas, in Arguineguín area. Porf, maybe you heard of it...?
I have heard of it, yes. It's not the only one with black sand, most beaches in Canarias have that volcanic origin, but in Marañuelas it seems to be specially dark.
There are others, in contrast, where the sand is golden: it's sand from the Sahara Desert and carried by the wind. The most famous one is Las Teresitas in Tenerife, but there are several like this throughout the archipelago.