Exposure to the natural environment is increasingly considered to benefit psychological health. Recent reports in the literature also suggest that outdoor exposure that includes recreational pursuits such as surfing or fishing coupled with opportunities for social interaction with peers may be beneficial to Armed Forces Veterans experiencing Post-Traumatic Stress Disorder (PTSD). Two studies were conducted to evaluate this possibility. In particular, these studies aimed to test the hypothesis that a brief group outdoor activity would decrease participants’ symptoms as assessed by established measures of PTSD, depression, anxiety and perceived stress, and increase participants’ sense of general social functioning and psychological growth. Experiment one employed a repeated measures design in which UK men and women military veterans with PTSD (N = 30) participated in a group outdoor activity (angling, equine care, or archery and falconry combined). Psychological measures were taken at 2 weeks prior, 2 weeks post, and at 4 month follow up. We obtained a significant within participant main effect indicating significant reduction in PTSD symptoms. Experiment two was a waitlist controlled randomised experiment employing an angling experience (N = 18) and 2 week follow up. In experiment 2 the predicted interaction of Group (Experimental vs. Waitlist Control) X Time (2 weeks pre vs. 2 weeks post) was obtained indicating that the experience resulted in significant reduction in PTSD symptoms relative to waitlist controls. The effect size was large. Additional analyses confirmed that the observed effects might also be considered clinically significant and reliable. In sum, peer outdoor experiences are beneficial and offer potential to complement existing provision for military veterans with Post Traumatic Stress Disorder.