Cetaceans, including minke whales, short-beaked common dolphin, and Pacific white-sided dolphins, are frequently observed or reported as bycatch in the coastal waters of the East Sea/Sea of Japan. The occurrence of cetaceans may be influenced by physical and biological oceanographic processes, including coastal upwelling, thermal fronts, cold-water events, and associated changes in primary productivity and prey aggregation. However, the relationships between cetacean occurrence and coastal to mesoscale oceanographic variability in this region remain poorly understood because few studies have integrated cetacean sighting records with satellite-derived environmental datasets to guide observation planning. Therefore, this study primarily aims to develop a deep learning-based environmental suitability model for cetacean detection in the East Sea/Sea of Japan using multi-platform field observations. Cetacean occurrence data are collected through integrated field surveys designed to support model development. The observation system consists of helikite-based broad-scale monitoring, drone-based close-range imaging, and vessel-based sighting surveys. Both cetacean presence and absence, along with observation conditions and environmental data, are collected to develop the deep learning model. The model uses environmental variables, including sea surface temperature, chlorophyll-a concentration, thermal front intensity, and upwelling-related indices, as input features, with cetacean observations collected from the multi-platform survey system as output variable. The developed model identifies major cetacean species or species groups and quantitatively evaluates the influence of environmental variables on detection probability. Furthermore, the model enables analysis of the potential relationships among physical oceanographic processes, productivity-related conditions, and the probability of cetacean occurrence. Therefore, this study is expected to improve our understanding of the relationships between cetaceans and their marine environment in the East Sea/Sea of Japan and to provide a practical framework for selecting observation areas based on physical oceanographic conditions.