This dive site, Shikotsuko Lake, is renowned for having Japan's highest water quality for five consecutive years, boasting exceptional clarity that can reach up to 50 meters from January to June. It offers a unique freshwater diving experience, including the opportunity for ice diving during the colder months, typically from January to March. Additionally, adventurous divers can undertake a distinctive river drift dive into the river that drains from the lake, providing a different perspective of this pristine environment.
The lake is home to a variety of fascinating marine animals and plants. From July to September, divers can spot endemic species of ducks and water plants, along with blue-winged carp, rainbow trout, and red-bellied shrimp. The river drift dives specifically offer sightings of rare blue and white carps. A particularly special time is from mid-October to the end of November, when the spawning of rainbow trout occurs, allowing divers to observe red-bellied trout displaying vibrant nuptial colors up close.
The best time to visit Shikotsuko Lake depends on the desired experience. January to June offers peak visibility of up to 50 meters, while ice diving is exclusively available from January to March. For observing the lake's diverse endemic species, July to September is ideal. Trout spawning season in October and November provides a spectacular display of red-bellied trout. Divers should be prepared for cold water, especially during the ice diving season, and those attempting the river drift dive should be aware of potential currents.
