dark, colorful and lighted interior of the cave of algar de carvão, terceira - azores portugal

algar angra attraction azores açores basaltic black caldeira carvao carvão cave cavern caving coal colorful crack dark deep destination europe explore formation geologic geological geology grottoes guilherme heroismo illuminated inside interior island judeu lava light lighted moniz park porto portugal portuguese rock roofs scenic speleology stone terceira textured touristic travel tube tunnel underground volcanic volcano wall