Shiratani Unsuikyo Ravine
Shiratani Unsuikyo Ravine is a natural forest with giant boulders, old hollow trees, waterfalls, and many rare species of plants and moss. It is located in the north of Yakushima Its temperate coniferous forest of 424 ha sits at an elevation of 600–1200 m. The ravine is home to Japanese fir (Abies firma), Japanese cedar trees (sugi in Japanese) (Cryptomeria japonica), and Japanese hemlock (Tsuga sieboldii), as well as more than 550 species of moss.
The hiking trails along the ravine pass some of the oldest sugi trees on the island; those older than one thousand years are referred to as yakusugi as they are found only here. Hiking trails also pass a riverside spot with large moss-covered boulders, including Taikoiwa Rock or “big drum boulder.” Here visitors can get a spectacular view of the highest peaks on the island.
The ravine has three main hiking courses. The short one-hour Yayoi Sugi course is named for a sugi dating to the Yayoi period (approx. 300 BCE–300 CE). The longer three-hour Bugyo Sugi course passes a handful of extraordinary yakusugi. Finally, the four-hour course around the Taikoiwa Rock also passes many yakusugi and ends with a magnificent view of the mountain range of central Yakushima.