Lake Yamanaka is the largest of the Fuji Five Lakes in surface area and the highest in elevation. It is the third highest lake in Japan, with a mean surface altitude of . It is also the shallowest of the Fuji Five Lakes, with a maximum water depth of . It was formed by lava flows from an ancient eruption of Mount Fuji. It is drained by the Sagami River and is the only of the Fuji Five Lakes to have a natural outflow.