In 1989, Gunther Holtorf and his wife Christine set out on what was meant to be an 18-month tour of Africa. 25 years later, with more than 885,000 km (550,000 miles) on the clock and 177 countries visited, Gunther is still going. The former airline executive has travelled the equivalent of 20 times around the planet in the same vehicle—which he calls Otto.

On a recent tour of Vietnam, Canadian-born photographer David Lemke joined Gunther on one section of his epic journey to talk about the road trip of a lifetime.