On August 24, 2023, the Japanese government and Tokyo Electric Power Company began the release of nuclear contaminated water into the ocean from the Fukushima Daiichi Nuclear Power Plant. This action is anticipated to negatively affect coastal and marine tourism. This study investigates public attitudes and perceptions towards the release of nuclear contaminated water through big data analysis and examines its impact on the Korean coastal and marine tourism industry. The study proposes measures to revitalize this industry. From August 24 to September 24, 2023, 23,138 Korean text data were collected through Naver and Google channels. Sixty keywords were identified through word frequency analysis, and a network was constructed using semantic network analysis to check centrality indicators. Through CONCOR analysis, the network was divided into three clusters: nuclear contaminated water release, risk perception, and tourism attitude change. The analysis confirmed high public attention and the negative impacts of Japan's nuclear contaminated water release. Notably, direct effects on the marine environment and domestic coastal cities were observed. The public showed significant changes in travel, food consumption, and accommodation bookings related to coastal and marine tourism, expressing concerns about health and safety. This study contributes to crisis management and communication strategy development in coastal and marine tourism. It also validates the methodological approach of understanding social phenomena through big data analysis and provides vital insights for researching the impact of environmental risks on coastal and marine tourism. Specific measures to revitalize the Korean coastal and marine tourism industry were proposed, emphasizing the necessity of introducing a safety certification system, providing real-time safety information, and establishing an emergency response system.