He authored a PADI Underwater Digital Photographer Distinctive Specialty in 2001, co-authored An Essential Guide to Digital Underwater Photography in 2004, as well as its sequel An Advanced Guide to Digital Underwater Photography in 2007. Mathieu is a regular contributor to international diving publications, and has been a speaker or judge at numerous international underwater photography events. Mathieu is always happy in the water, be it capturing the beauty of large reef denizens, majestic wrecks, or the tiniest of subjects. Mathieu is also one of the judges of the 2011 Underwater Festival.