Corals are under various form of threat including bleaching due to global warming. This presentation will review remote sensing methods to monitor the conditions of coral reefs on several different scales, from the highest above the sea to underwater using satellite and aerial images as well as underwater photographs. Field surveys were performed in Tidung Island, Java Sea, Indonesia, and we chose the satellite images provided by Sentinel-2 (10-m resolution) and Planet (3-m resolution) taken close to the field survey dates. For comparative purposes, we also use the aerial images from the Geospatial Information Authority of Japan and field data from the Biodiversity Center of Japan for classification and testing of the data from the Sekisei reef, Okinawa, Japan. We assess the potential of different monitoring methods for obtaining optimum results under varying conditions.