Diving in Japan: an Overview A dive under Japanese Waters Geographical Position & Extreme pointsTerritory and PopulationCoastlinesA marine biodiversity hotspot Islands The 5 main islands of JapanTwo extended archipelagos: the Nanpō and Nansei islandsMain regions of Japan Currents Main CurrentsWarm WaterCold WaterA closer look at the Kuroshio-Oyashio system Seas Japanese seas and oceansStraits and inletsMajor Lakes Climate & Seasons Climate & SeasonsRainy seasons and cyclonic stormsThe 4 Japanese seasons Biodiversity