Do you see a scary face looking back at you? The hollow-appearing eyes, narrow nose, and slash of a mouth are inundated patches of shallow Lake Eyre (pronounced "air"). Deep in the desert country of northern South Australia, Lake Eyre is an ephemeral feature of this flat, parched landscape. When seasonal rains are abundant, water fills the lakebed to some degree. During the last 150 years, Lake Eyre has filled completely only three times. When brimming, it is Australia's largest lake.