Taken from Wikipedia:
Kazimierz Nowak (January 11, 1897 – October 13, 1937) – was a Polish traveller, correspondent and photographer, born in Stryj. After the First World War he lived in Poznań.
From 1931 to 1936, he traveled alone, on foot and by bicycle across Africa, covering a distance of 40,000 km: from Libya to South Africa and back to Algeria. He seems to be the only man in the world to have done it. His accounts of the travel were first published jointly as late as in 2000, as a book entitled Rowerem i pieszo przez Czarny Ląd (By bicycle and on foot across the Black Continent). He died in Poznań from pneumonia as a consequence of emaciation of the body due to the travel, malaria and a leg surgery.