halsanefshellir cave made of basalt columns on reynisfjara black sand beach, iceland, inside view of the cave

arch basalt beach black sand cave cavern ceiling cliff coast column empty erosion europe formation frozen geology halsanefshellir hexagonal haiexcl lsanefshellir iceland icelandic inside landmark landscape lava mountain myrdal natural nature people outdoor pillar raw reynisdrangar reynisfjara rock shore south stack stone tourism travel vault vertical view vik volcanic wall