The Burke and Wills expedition (1860–61), aimed to cross Australia from bottom to top and back again. This huge area of mostly desert was mostly unknown to European settlers at the time.
Starting in Melbourne and travelling about 3,250 kilometres (2,020 miles), they actually made it to the Gulf of Carpentaria in the far north, although swampland stopped them from reaching the water.
The return journey was plagued by problems. When they finally reached an agreed meeting place at Cooper Creek (about halfway back to Melbourne), they found the rest of their party, after waiting months, had abandoned it just hours earlier. Burke and Wills died in the area from malnutrition around 30 June 1861.
Of course, this is a quick telling of the story. If you want to know more, here is a Wikipedia page about the expedition.