Beginning 190,000 years ago, Undara Volcano in far north Queensland erupted, not with a bang but a long, seething gush of lava. Undara disgorged a colossal 23 cu.km of molten mayhem. It spread across the plains and filled ancient river valleys to the brim. Over time, the lava atop these deeper valleys cooled to form a dark, hard crust. Meanwhile, below decks, the liquid lava kept surging downstream. In essence, as it moved on, the lava fabricated its own insulated pipeline. By the time Undara was a spent force its farthest run had travelled 160km. In recent geology, no other single volcano on Earth has a longer lava flow. Visitors can see the remnants of the lava pipeline at Undara Volcanic National Park. Nearby the limestone formations of Chillagoe-Mungana Caves National Park and the distinct sandstone ravines of the region are also a delight to geology lovers.