Lake Sai

Lake Sai (西湖, Saiko) is the middle lake of the Fuji Five Lakes. It is unique from the other lakes in that it is surrounded by steep, wooded slopes on all sides, and Mount Fuji is only clearly visible from its western point. Like its neighbours, Shojiko and Motosuko, Lake Sai was formed as a separate lake from an eruption of Mount Fuji in the 9th century. Geologically, these three lakes remain connected by underground waterways, which ensures their water levels stay synchronized.

There are some camping sites around the shoreline and a handful of coffee huts and restaurants, as well as a small village at the western end, but Saiko is noticeably less developed than Lake Kawaguchi. The lake’s clear waters reach depths of over 70 meters, making it popular for kayaking and trout fishing. Slightly to the south visitors can find the Narusawa Ice Cave, Fugaku Wind Cave, Lake Saiko Bat Cave, and the Aokigahara Jukai forest. This dense “Sea of Trees” offers several well-marked walking trails that showcase the unique volcanic terrain of the area. Because of its quiet atmosphere and proximity to these geological wonders, the lake remains a favored spot for nature enthusiasts seeking a retreat from more commercialized tourist hubs.

Access
Station / Stop	Line / Bus	Access Details
Kawaguchiko Station	Saiko Sightseeing Bus (Green Line)	Take the Green Line bus to the Saiko Bat Cave or Iyashi no Sato stops (approx. 25-40 mins)
Lake Saiko	Blue Line / Narusawa/Shojiko/Motosuko Bus	Connects the southern caves and Aokigahara forest area to Kawaguchiko Station