Dewa Sanzan ("three mountains of Dewa") are three sacred mountains in Yamagata Prefecture, each with a shrine on or near its peak. The mountains are named Haguro-san, Gas-san and Yudono-san and remain centers of mountain worship. Representing birth (Haguro-san), death (Gas-san) and rebirth (Yudono-san), the mountains are usually visited in that order.
Part of Dewa Sanzan's appeal is its remoteness. Yamagata's heavy snowfall makes travel in the mountains difficult during the winter months when only Haguro-san remains open. The best time to visit is between July and mid September when all three shrines are open to pilgrims and tourists.