Kati Thanda-Lake Eyre, the world's sixth-largest lake, is just off the Oodnadatta Track. It's usually dry but a couple of times in recent years it has filled with flood waters running in from Queensland. When this happens (only once every decade or so), the explosion of bird life is astonishing! It's also the lowest point on the Australian continent, bottoming-out at 15.2m below sea level.