 In 1862 he took part in Karl Klaus von der Decken's expedition in East Africa, where the two men made a partial ascent (4280 m) of Mount Kilimanjaro.In 1863 he traveled with von der Decken to the Seychelles and the Mascarenes, and during the following year, Kersten visited Madagascar, the Comoros and Mafia Island.In 1865 he returned to Europe.