Coastal tourism is a strategic sector in global economic development, but it faces serious challenges related to sustainability. Understanding tourist perceptions is crucial for maintaining destination competitiveness. Moreover, sentiment analysis based on online reviews offers new opportunities to explore tourist opinions broadly and in real-time. This study aims to conduct a Systematic Literature Review (SLR) of research discussing the application of sentiment analysis in coastal tourism from 2015 to 2025. The literature search was conducted in major databases, namely Scopus, ScienceDirect, IEEE Xplore, and ACM Digital Library, using predetermined search strings. Based on the initial search results obtained from 190 articles, after the duplication removal and Quality Assessment (QA) processes, only 36 articles met the criteria and were further analyzed. The results demonstrate an increasing trend in publications since 2018, peaking in 2024. These studies are spread across various regions of the world, with a predominance of Southeast Asia and Europe. TripAdvisor and Google Maps served as the primary data sources. Analysis methods included lexicon approaches, Machine Learning (ML) algorithms (Naive Bayes, Support Vector Machine (SVM), k-Nearest Neighbor (kNN), Random Forest), Deep Learning (DL) (Convolutional Neural Networks (CNN), Long Short-Term Memory (LSTM)), as well as hybrid approaches and Large Language Models (LLM). The labeling schemes used varied, ranging from binary and three-class to emotional categories, satisfaction dimensions, and the Kano model. Overall, tourist reviews of coastal destinations were positive, although complaints about cleanliness, price, service, and sustainability were common. These findings confirm that sentiment analysis is a crucial tool for understanding tourist experiences and can support sustainable coastal tourism management globally.