North of Kisarazu, the flat industrial shore of Tokyo Bay gives way inland to the Boso hills, a rumpled landscape of low, steep ridges and narrow valleys covered in forest. The hills are not high, but they are surprisingly wild, cut by deep ravines and rivers that wind through them in tight loops, and they offer some of the best riding close to Tokyo.
The Yōrō river is the star. Its valley, the Yōrō Keikoku, is a gorge of sandstone cliffs, waterfalls and forests, especially beautiful in late November and early December, when the maples turn red and gold. Awamata Falls, a long, shallow cascade over a rock slope, is one of the most popular spots. The Kominato Railway, a rural line with old diesel trains, runs through the valley, and its little wooden stations are charming.
As a high point, the ridges above the gorge offer views over the folded hills, with the bay and the industrial shore visible in the distance. On clear days, Mount Fuji can be seen far to the west, across the bay.
For riders, the roads through the Boso hills are a joy: narrow, twisting, with short climbs and descents, and generally light traffic, except in the foliage season. Surfaces vary, and some roads are narrow, with blind corners and gravel. Watch for wildlife, including deer, monkeys and wild boar. Fuel and food are available in Kisarazu, Ichihara and the small towns in the hills, but stations are sparse in the interior, so fill up before you go.