Take a walk in the dark throughout Nahuku, known as the Thurston Lava Tube, a 500-year old lava cave situated within Hawaii Volcanoes National Park. Lava caves like this are shaped when a river of lava steadilyerected solid walls and a ceiling. When the lava stream stops and the last of it pass downhill, a cave is formed. These caves can be a few feet high and only few yards long, or they can extend for miles with high ceilings. The Thurston Lava Tube is an extraordinary example of a huge lava cave. Lit by electric lights, with a flat rock floor and a ceiling high enough in the centre, this is a great prologue to lava tube geology. The solidified drips and waves of once-liquid lava rock evidently show the molten forces that formed this cave.