Social media has become an important source of travel information, inspiration, and social influence. This role may be particularly significant in adventure tourism, where experiences such as trekking, rafting, paragliding, scuba diving, and camping are frequently represented through visually engaging photographs, short videos, stories, and user-generated content. Beyond providing destination information, social media exposes individuals to the travel experiences of friends, peers, influencers, and other users, and this continuous exposure may create the perception that others are enjoying rewarding experiences one is missing, generating Fear of Missing Out (FOMO). Although FOMO has attracted growing attention in tourism research, most existing empirical work has examined it as a direct predictor of travel intention within general or influencer-driven tourism contexts, leaving its role as a sequential, mediating mechanism in adventure tourism specifically, and its distinction from actual behavioural participation comparatively underdeveloped. This paper addresses that gap by proposing a conceptual framework explaining how social media stimuli generate FOMO, how FOMO influences adventure tourism travel intention, and how travel intention contributes to actual participation in adventure tourism. Drawing primarily on Social Comparison Theory and supported by the Theory of Planned Behaviour and Uses and Gratifications Theory, the paper conceptualises FOMO as an affective mechanism that links social media stimuli to travel intention within a sequential pathway: social media stimuli → FOMO → travel intention → adventure tourism participation. The paper contributes to tourism literature by integrating social media exposure, emotional response, intention formation, and behavioural participation within a single, testable framework, and by explicitly separating psychological readiness (intention) from behavioural execution (participation). It also identifies boundary conditions under which the proposed pathway is more or less likely to hold. It provides a foundation for future empirical research examining how digitally mediated social experiences influence adventure tourism behaviour.