An avid outdoorsman, much of Hall-Jones's writing focused on the natural history and wilderness areas of southern New Zealand. He also published works on the history of Antarctica, the Himalayas, Patagonia, and the Rocky Mountains. Hall-Jones would often begin research for his books by exploring the wilderness of an area by flying, kayaking, trekking or camping in a region. He would write during the winters when the weather was colder. In all he published 34 historical books.