Purpose: Stand up paddle boarding (SUP) is a rapidly growing sport and recreational activity where only anecdotal evidence exists for its proposed health, fitness and injury rehabilitation benefits. Methods: A total of 10 internationally and nationally ranked elite SUP athletes volunteered to participate in this study. Elite SUP athletes were assessed for their maximal aerobic power on an ergometer in a laboratory and compared to other water based athletes. Field based assessments were subsequently performed utilising a portable gas analysis system and a correlation between the two measures was performed. Results: The mean VO2max (relative) was significantly higher (P =.037) when measured in the field with a portable gas analysis system (45.48±6.96ml/kg/min) when compared to laboratory based metabolic cart measurements (43.20±6.67ml/kg/min). There was a strong, positive correlation (r=0.907) between laboratory and field maximal aerobic power results. Significantly higher (P=0.000) measures of SUP paddling speed (m/s) were found in the field when compared to the laboratory ergometer (+42.39%). There were no significant differences in maximal heart rate between the laboratory and field settings (P=.576). Conclusion: The results demonstrates the maximal aerobic power representative of internationally and nationally ranked SUP athletes and shows that SUP athletes can be assessed for maximal aerobic power in the laboratory with high correlation to field based measures. The field based portable gas analysis unit has a tendency to consistently measure higher oxygen consumption. Elite SUP participants display aerobic power outputs similar to other upper limb dominant elite water based athletes (surfing, dragon boat racing and canoeing).