Travel Between the Lines Adult Coloring Book: Inspirational Coloring for Globetrotters and Daydreamers About the Author Geoff and Katie Matthews quit their corporate jobs in 2013 to become permanent world travelers, and have visited more than 50 countries as expatriates and visitors. Today, they create travel coloring books for grown-ups who love to explore, creating unique, beautiful and detailed illustrations based on their real-life travel photographs.