It's a series of zip lines, rope bridges, shaking wood bridges with several planks missing, and other obstacles that you go through. Each increasing in challenge and skill level.
There is no braking device, so at the end of each zip line there is a bumper thing that your run into and a pile of wood chips. Let me tell you how soft those things feel when you slam into them back first, legs flailing. I tried several methods: not moving trying to stay as still as possible to remain facing forward, fail. Kicking my legs to keep myself facing forward, minimal success. Just giving in to the fact that I was going to slam into the end of the thing back first, success! I landed 1 out of about 10 zip lines correctly. The others were nothing short of a disastrous wreck!
I haven't had this much fun in a long time though, and can't wait to go back again...
From Kadena Gate 1 Exit and Turn Right (going North on 58)
Stay on this road all the way to Onna
When you see the Residence Hotel (huge and on your left on the ocean) make a sharp Left
Stay on that road for about 10 minutes. The Forest Adventure office will be on your left