Lonely Planet review
Accessible from July to September, Gas-san (1984m) is the highest of the three sacred mountains. From the trail head at Hachigōme (八合目; eighth station), the route passes through an alpine plateau to Kyūgōme (九合目; ninth station) in 1¾ hours, and then grinds uphill for another 1¼ hours.
Perched on the summit is the tiny, yet deeply spiritual Gassan-jinja . To enter the shrine, you'll first need to undergo a ritual purification: bow your head to receive the priest's benediction, then brush yourself from head to toe with the slip of paper, placing it afterwards in the fountain. Beyond the gate, visitors traditionally make a circuit of the inner shrine. Note that photography is not permitted inside.
From here, the pilgrimage route presses on towards the steep descent to Yudono-san. This takes another three hours or so, and you'll have to carefully descend rusty ladders chained to the cliff sides and pick your way down through a slippery stream bed at the end of the trail.