Coastal environments are widely recognized as valuable public health resources and therapeutic landscapes. However, limited research has examined how specific coastal interactions that foster close connections with nature influence health outcomes. This study investigates the relationship between the frequency of engaging in high-nature-interaction coastal activities―e.g., beach walking, wildlife spotting, water sports, mountain biking, spending time on the beach, beach sports, watching the sunset, seagoing, and shell collecting― and health outcomes among visitors to the Belgian coast. Using a dataset of 1,939 (...) responses, we analyze how the frequencies of these activities over the past year are associated with self-reported mental and general health. Grounded in the Granular Interaction Thinking Theory (GITT) and employing Bayesian GITT Framework analytics, the study identifies distinct patterns in these associations. While frequent engagement in activities, e.g., beach walking and beach sports, is positively linked to both mental and general health, spending time on the beach and shell collecting are unexpectedly associated with negative health outcomes. Watching the sunset is negatively associated with general health, while mountain biking and water sports show negative associations with mental health. In contrast, wildlife spotting exhibits a positive association with mental well-being. These findings highlight the complex interplay of environmental factors, visitor perceptions, and biophysical-psychological interactions in shaping health outcomes. The study emphasizes the need for targeted coastal management strategies to enhance the therapeutic benefits of blue spaces and calls for further research to elucidate the mechanisms underlying these associations. (shrink)