Scattered across Saudi Arabia's vast deserts and mountains lie more than 2,500 volcanic craters, relics of a fiery geological past that continues to intrigue scientists and thrill adventurous travelers today. The last known eruption occurred in 1256 near Madinah, leaving a 20 km lava trail that is still visible. The Kingdom's volcanic fields cover around 4.6 percent of its total area, offering some of the most breathtaking geological sights in the region.