本栖湖 (or 'Motosu-ko' or Lake Motosu
) is the ninth deepest lake of Japan, at 140 meters, and part of the Five Lakes of Mount Fuji
. This lake, along with Lake Sai
and Lake Shoji
, was formed by lava flowing across what is now Aokigahara Jukai Forest and into the enormous lake that once dominated the area, and these three lakes remain still connected by underground waterways.