DiveZone Tokyo is the most active, fun group of scuba divers in Tokyo. Whether you are a recreational scuba diver or technical diver or want to learn how to, we aim at providing many fun diving trips and diver courses so that people can get more opportunities to dive and spend time in the water. We dive all year around drysuit (winter) and wetsuit (summer).
http://www.city.chiyoda.lg.jp/shisetsu/koen/073.html