Accessible from July to September, Gas-san (1984m) is the highest of these sacred mountains. From Hachigōme (八合目; eighth station), the route passes through an alpine plateau to Kyūgōme (九合目; ninth station) in 1¾ hours, then grinds uphill for another 1¼ hours. Before entering deeply spiritual Gassan-jinja you must be 'purifed': bow to receive the priest's benediction, then brush yourself head-to-toe with the slip of paper, placing it afterwards in the fountain. Beyond the gate, photography is prohibited.
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.