Diving is Japan is famously associated with Okinawa and its subtropical waters. With all the focus on Japan’s diving in Okinawa, few international visitors venture to the Izu Peninsula for tourism let alone with the desire to explore its marine life. The tourism in this region is catered to Japanese locals who go diving in the popular spots such as Futo, Atami, Cape Ose and Mikomoto (known as Hammerhead Island).
However, very few have knowledge of the dive sites in Atagawa. Kazuhisa Noguchi is the manager of Atagawa Dive and Pono Café. He started scuba diving when he was 10 years old. Now, at 43, he is managing his own family-run dive shop. He holds the secret to what he says is the best diving in the entire Izu Peninsula.
In Kazuhisa’s opinion, the best diving site in the peninsula is Kagikakine which is referred to as “Big Rock”. The reason? Since it’s not the most popular diving site in the Peninsula, there are fewer tourists and divers which has left the soft corals relatively undisturbed.
More importantly, is the presence of hot springs throughout the peninsula and in Atagawa. This is largely due to geological reasons. Approximately 20 million years ago. Izu was an isolated group of submarine volcanoes which belongs to the Philippine Sea Plate. This tectonic plate started moving hundreds of kilometers north towards the Honshu tectonic plate and the two plates collided, forming the present-day peninsula about 600,000 years ago .
Following the formation of the peninsula, there was a large amount of volcanic activity forming large volcanoes. Subsequently, smaller groups of monogenetic volcanoes, which only erupt once, though these eruptions can last a long period of time, were established . Presently, this type of volcanism still exists in Izu and the name for this group is the Izu Tobu volcano group. Since the Philippine sea plate is still pushing up into the Honshu Plate where the Izu peninsula is located, this is still creating land forms and the famous hot springs that are strewn across the entire peninsula .
But how does this effect the diving? Since Atagawa also sees a lot of volcanic activity, hot springs are prevalent and the water from the hot springs is moves into the surrounding sea. Whether these hot springs are releasing water from underwater volcanoes or are releasing hot water from geysers in the earth’s surface is unknown. According to Kazuhisa, on days where the current is absent or not strong, the hot streams of water enter the area increasing the water temperature and bringing more nutrients to the surrounding ocean. He thinks that this allows the soft corals to be healthier because of the influx of nutrients. Besides, healthy corals mean healthy marine life .
Some of the marine life that can be observed in Atagawa are soft corals, Ecklonia cava which is an algae common in Japan and South Korea’s waters , many species of crustaceans, nudibranch, rock fish, sculpins, rays and maybe the occasional turtle! There has even been a new species of velvet fish found in the peninsula in 2010 ! So there is much more to be found!
Atagawa Dive is the primary outfitter for diving in Atagawa. They also offer some of the lowest rates for diving on the peninsula. It is possible to go diving without a guide in Atagawa because Kazuhisa has established guidelines set up 1 meter apart from the dive starting point. However, it is required that you go with a dive buddy and it is recommended that you have completed 30 dives. Since Atagawa Dive’s site is in Japanese, these are the costs for diving and equipment:
2 tank dives + lunch at Pono Cafe and free coffee: 8500 Yen
1 tank dives + lunch at Pono Café and free coffee: 6500 Yen
Extras: *For those who want to do additional diving besides the Dive Packages
10 liter Tank (+2300 Yen) Upgrade Tank Capacity 12 liters 1 tank (+500 Yen) *For set package users
Upgrade Tank Capacity 14 liters 1 tank (+1000 Yen) *For set package users
Upgrade to Nitrox Tank 12 liters 1 tank (+3000 Yen) *For those who want swift diving experience
Underwater Diving Guide:
1 dive /person (+5000 Yen) *Limited time offer
2 dive/ person (+7500 Yen) *For beginners who want a more enjoyable experience
Mask, fin and snorkel set: 2200 Yen
Wet suit: 2200 Yen
Boots: 1100 Yen
Regulator: 3000 Yen
BCD: 3000 Yen
1 dive: 3500 Yen
2 dives/whole day: 5000 Yen
#Solo Divers are welcome but will be required to go with a Diving Guide!
#At Atagawa Diving Service, they provide tasty meals with our diving set packages. You may choose to bring your own food, but there is no discount.
Below are the Maps of the dive sites.
Translations completed with the assistance of Rob Hashiba of The Other House!
 Izu Peninsula Geopark. (2012). Main theme of the Izu Peninsula Geopark. Retrieved from: http://english.izugeopark.org/theme/subtheme5/
 White, J. D. (1991). The depositional record of small, monogenetic volcanoes within terrestrial basins. Society for Sedimentary Geology, 45, 155-171.
 Ocean Health Index. (2017). Coral Reefs. Retrieved from: http://www.oceanhealthindex.org/methodology/components/coral-reefs-area
 Bayani Cardenas, M., Lagmay, A. M. F., Andrews, B. J., Rodolfo, R. S., Cabria, H. B., Zamora, P. B., & Lapus, M. R. (2012). Terrestrial smokers: Thermal springs due to hydrothermal convection of groundwater connected to surface water. Geophysical Research Letters, 39(2), 1-6.
 Yokohama, Y., Tanaka, J., & Chihara, M. (1987). Productivity of the Ecklonia cava community in a bay of Izu Peninsula on the Pacific coast of Japan. Journal of Plant Research. 100(2): 129-141.
If any of this information is ever incorrect or outdated, please feel free to contact us. Bioonthego is all about using the most up to date science and information.