On the way back home we found a lava tube. On this one, the roof collapsed but near to the volcano there is one that’s still closed and looks like a real tube. We crossed it all, it was impressive how long it was.
"On sait bien où l'on veut aller, mais on ignore quand, comment, par quel chemin on y parviendra. Inutile de s'en trop soucier d'avance; on verra bien..." (Théodore Monod)