Tourism is an inherently emotional experience. Yet, for decades, research has relied predominantly on rational-choice models and self-report surveys, assuming that tourists make deliberate and conscious decisions. Recent advances in neuroscience and consumer behavior studies challenge this assumption, revealing that up to 95% of our decisions are driven by unconscious processes and emotional responses. This paper introduces a neuroscientific framework for decoding tourist behavior. It is based on dual-system theory (System 1 and 2), predictive brain models, and physiological measurement techniques such as EEG, eye-tracking, GSR, facial coding, and implicit association testing. Through real-world case studies in food tourism, hospitality, and cultural heritage, we show how these tools uncover unspoken emotional responses that shape memory, satisfaction, and behavior. A dedicated section addresses sustainable tourism, illustrating how neuroscience-informed nudges can help align tourist behavior with ecological values without compromising enjoyment. Finally, we explore implications for tourism operators, marketers, and policymakers, emphasizing how emotion-driven design and communication can foster more engaging and sustainable tourism experiences.