If you're looking for the straightest route to Jomon Sugi, you'll hike 22km round-trip from the Arakawa trailhead. The route follows an old railroad and passes two restrooms before entering steeper terrain. It can be done in one day or two days.
People who have a copy of Lonely Planet know about the two-day course that starts in the south, cuts through the center, and finishes a bit west with a few options along the way. This is a beautiful trek that takes you past weather-battered skeleton trees, through a high-altitude peat bog, over Yakushima's highest peak, past Jomon Sugi, and down through the Mononoke forest wonderland. However, the first day is especially long, the 'mountain huts' are pretty barren, and I've met quite a few rain-beaten folks on their way down. If you do this route, please start early the first morning, and check for warnings from the Japanese Meteorological Agency.
There are plenty of other beautiful hikes as well, which you can uncover with a little reading. I offer a similar route which cuts the first day off of the Lonely Planet hike.
Characteristics of hiking in Yakushima
1. Yakushima has a lot of drinkable water running down the mountains, so much that they've been mulling the idea of filling oil tankers with drinking water for their return trip to the Middle East. I admit I have skipped water holes only to run out of water several hours from the next source. How much you need depends on your route, the weather, and your personal needs, but leave the tablets and filters at home.
2. Yakushima has a lot of rain. Check the weather report for effective warnings before you head out, lest you be confronted by an impassable river crossing. Locals may seem overly concerned by a little rain, but hikers going missing (sometimes permanently) every year. Acknowledge your limits. It's also a good idea to bring nice rain gear and double bag your dry stuff inside your pack, no matter the weather forecast. (Yakushima's interior gets double the rainfall of the coasts.) That said, don't be turned off by the rain; enjoy it.
3. If you should get lost, follow normal safety procedures, but head up, not down. Don't follow rivers, because you'll probably find a waterfall over a steep drop before you find any people. Instead, head for high ground, because the highest mountains have trails at their peaks, and you can often get a cell phone signal as well.
4. Rent everything you don't want to schlep around Japan. You can rent all kinds of hiking and camping gear at the outdoor stores on the island. But no guarantees for big or tall people or people with big feet.
5. Yakushima also has no large predators, but there are a few nasty critters to watch out for:
- Snakes: Particularly the Mamushi, which looks a bit like a medium diamond-back minus the rattle, but usually stays off the trails in the daytime.
- Suzume-bachi: A huge, orange Asian wasp. Don't worry if it's just buzzing by, but if it starts clicking, back off if you value your life.
- Leeches: These are not the fat monsters of dramatic documentaries, and if you leave them be, they will just fall off after about 20 minutes of (fairly harmlessly) sucking your blood. They're spit contains both an anesthetic and an anticoagulant, so you might not even notice that one has bit you until it falls off and you notice you're leaking blood from a small hole. They have been expanding their realm lately, but you're still unlikely to meet them on the most popular trails. On the Western side of the island—I don't know why—they have an affinity for belly blood.
- Mice: Yakushima has really cute, endemic mice, but make sure your food is sealed overnight. Deer also like to rummage through packs for food.
- Bugs: While there are bugs that
bite like black flies that follow heat sources and a few horse flies in summer, while you are in the mountains there are probably not enough to merit bug spray unless you have allergies. Spiders are probably the least of your worries, but killing them is bad luck.
There are poisonous plants, too, but if you don't eat them, they won't eat you.
7. Plan your toilet stops. Remember that the popular trails can see hundreds of folks in a day, and everybody is drinking unfiltered water. Yes, the monkeys do their business anywhere they want, but humans can buy a disposable toilet pack to take hiking. (Yes, even for urine!) Popular trails even have stations set up for use with your toilet pack. There are latrines at the mountain huts, but the contents of these is scooped out and carried down manually, and there is probably no toilet paper except in Shiratani. If you use toilets on the trail, you are encouraged to make a donation.
8. Carry out exactly what you carried in. Don't take home any walking sticks or plants. Don't wash your dirty dishes in the streams.
9. When in doubt, stay on the trail. I think this is a no-brainer, but Yakushima sees a lot of tourists, and this rule is meant for both preservation and safety.
10. Tent camping is only allowed at designated (paid) camp sites or around the mountain huts. Sorry, no free camping on the beach. Since Yakushima is mostly a big pile of granite without much soil, I recommend free-standing tents (or something you can tie down with a few rocks) if you plan to stay in the mountains. I don't recommend hammock camping in the mountains because the only trees suitable to hold your weight may be hundreds of years old and covered with delicate moss and lichens. (I haven't gotten around to finding hammock camping sites around the coastal areas or trying to hammock inside a hut out of season, but I'll let you know when I do.) There is public land with trees near rivers and coasts where you can take an afternoon siesta in a hammock, though.
For more guidelines, see my blog entry on Etiquette in Yakushima.