After Paul came back from his expedition around Africa he started to write a book about his...
What would you say, his journey or his travels (plural) if there is no other context? It seemed logical to me to use journey because it is not clear from this sentence that he made any other travels besides this African expedition.
But I was told that it is correct to use travels here because the meaning of the word travel is broader while journey usually means a trip from point A to point B so it is not correct for a travel around Africa.