The aim of this thesis was to investigate how physiological and environmental factors affect surfing performance. Studies were performed that assessed the effect of anthropometric and physiological characteristics of surfers on rank and ability, the effect of creatine supplementation on surfing performance and the effect of wave size, wave period and the ability of surfers on physiological and performance indices of surfing. Study one investigated the effect of the anthropometric variables on rank and rating of ability. This was measured across a sample of 79 surfers ranging from intermediate to professional surfers. Significant correlations were found for endomorphy (r = -0.366, P <0.01), sum of six skinfolds (r = -0.274, P <0.05), Body fat percentage (r = -0.268, P <0.01) and mesomorphy (r = 0.442, P <0.01). Findings suggest that levels of adiposity and muscularity might influence the potential for progression between intermediate and professional level surfing performance. Study two investigated the effect of physiological variables on the national ranking of 18 elite male junior surfers using assessments of maximal oxygen uptake, lower body explosive power, upper body power, agility, and balance. Partial correlations were used to account for the influence of age within the sample and a significant correlation was found between power output at (rp = -0.879, P <0.01). Findings suggest that power output at is an important factor for achieving competitive success in high performance junior surfers. Study three investigated the effect of short term (20g.day-1 for 5 days) creatine supplementation on body composition, repeated upper body anaerobic power and competition performance was assessed in 17 club level surfers. Testing comprised assessment of body mass and total body water using bioelectrical impedance analysis, a repeated upper body Wingate based on time motion analysis of competitive surfing. A two-way repeated measures ANOVA found no significant effects of supplementation on laboratory measures of anaerobic power or competitive performance. The fourth study investigated the effects of changes in wave conditions on physiological response and performance parameters of surfing. This was assessed using 39 surfers who participated in 60 surfing sessions where wave conditions were recorded and performance was measured using GPS. The study found that wave height was significantly related to energy expenditure (rp =-0.351, P <0.05), maximum ride speed (rp = 0.866, P <0.01), the standard deviation of maximum ride speeds (rp = 0.654, P <0.01), mean ride time (rp = 0.354, P <0.01), maximum ride time (rp = -0.296, P <0.05), the standard deviation of the ride times expenditure (rp = -0.344, P <0.01), mean ride distance (rp = 0.398, P <0.01), maximum ride time (rp = 0.318, P <0.05), minimum ride distance (rp = 0.268, P <0.05), standard deviation of the ride distances (rp = -0.362, P <0.01), percentage of total distance riding (rp = 0.310, P <0.05), percentage of time spent waiting (rp = -0.272, P = 0.05), percentage of total time spent riding (rp = 0.396, P < 0.01), percentage of total time in miscellaneous activities (rp = 0.471, P <0.01), total distance riding (rp = 0.310, P =0.05), total distance per hour (rp = 0.427, P <0.01). Wave period was found to be significantly related to average heart rate as a percentage of maximum (rp = 0.490, P <0.01), the percentage of time spent in the “easy” training zone (rp = -0.408, P <0.01), maximum ride speed (rp = 0.371, P <0.01), mean ride time (rp = 0.283, P <0.05), maximum ride distance (rp = 0.279, P <0.05), and the standard deviation of the ride distances (rp = 0.325, P <0.05). The ability levels of the surfers were found to be significantly related to average heart rate as a percentage of maximum (rp = -0.412, P <0.01), percentage of time in the “steady” zone (rp = 0.435, P <0.01), percentage of time in the “intermittent” zone (rp = 0.483, P <0.01), maximum ride speed (rp = 0.454, P <0.01), mean ride distance (rp = 0.392, P <0.05), standard deviation of the ride distances (rp = 0.264, P <0.05), percentage of the total distance riding(rp = 0.267, P <0.05), percentage of time paddling (rp = 0.364, P <0.05), percentage of time in miscellaneous activities (rp = -0.299, P <0.05), total distance riding (rp = 0.267, P <0.05) and average speed (rp = 0.428, P <0.01). This thesis has found that ability in surfing is related to anthropometric and physiological measures, creatine supplementation improves peak anaerobic power but does not significantly improve surfing performance in club level surfers and that wave conditions and the skill levels of surfers are significantly related to the physiological and performance parameters of surfing.