According to epidemiological findings, individuals who engage in more physical activity (PA) have a greater skin cancer risk, presumably due to time spent outdoors when performing PA. To better understand the relationship between PA and sun exposure, we conducted a 7-day observational study among both melanoma survivors (n=20, Mage=62.8 year, 55% female) and young adult first-degree relatives of melanoma survivors (n=20, Mage=26.5 years, 75% female). Participants wore ultraviolet radiation (UVR) sensors and completed daily reports on their outdoor activities. Multilevel analysis revealed that activities with more minutes of moderate-vigorous physical activity (MVPA) were associated with greater unprotected UVR exposure, B=.79, t=9.96, p<.01. This association was evident at both the between- and within-subjects levels. In other words, more active individuals had greater unprotected sun exposure (B=.88, t=6.57, p<.001), and unprotected UVR exposure was higher when individuals were performing an activity that involved higher levels of MVPA than was usual for them (B=.75, t=8.33, p<.001). In exploratory analyses, we found that the highest unprotected UVR exposure occurred during outdoor games (5 of 8 activities exceeding 200 J/m2 were in this category). Taken together, these findings confirm the link between outdoor MVPA and unprotected UVR exposure, and suggest outdoor games (e.g., golf, tennis) can be a particularly strong source of UVR exposure, contributing to skin cancer risk. These results highlight the need for interventions to promote sun protection during outdoor MVPA, including among high-risk populations and those that are less likely to use sun protection (e.g., young adults).