Water, or the lack of it.
Way back, in 1844, August 10th, Captain Charles Sturt led the Central Australian Expedition from Adelaide, along the Murray and the Darling Rivers before heading where no European had been before. The quest was to find the sea which Sturt and his sponsors believed occupied the heart of Australia.
The expedition's outfit consisted of: 16 men,11 horses, 30 bullocks.1 boat and boat carriage. 1 horse dray.1 spring cart.3 drays, 200 sheep for food, two sheep dogs, and four kangaroo dogs. The journey failed to find the mythical inland sea.
I made this sketch for the Illustration Friday topic of "water".