Zip lines are an absolute scream; although I've done it too many times to count, every time I head back to Costa Rica I hit either the Rincon or Monteverde lines. It never loses it's fun factor, no matter how many times you do it.
You're lucky you've got tall and strudy trees around you; I'm quite jealous as I would kill to set up a line or two on my property...
The really wild ones in CR are around 1/4 mile long and you hit around 35 MPH, suspended way the hell above the forest canopy. Best time to do them is in the fog, as you get a really eerie feeling of complete suspension since you have no visual clue as to how far the ground really is beneath you. Rincon has one that runs through a old volcanic canyon that has some nice rapids running through it. Although it's one of the shortest runs around, it's probably my favorite as there's some rock scrambling that goes on and brings you REAL close to the rapids at one of the end runs (thank God there are places still left on the planet that haven't let lawyers f**k up all the fun for a paying public willing to bear a few risks).
I've got a video of one of the first Monteverde runs that I did, which I synced Wagner's "Flight of the Valkyrie" to; it's pretty freaky.
What a b**chin' way to spend Summer weekends. I'd burn through pulleys like there's no tomorrow.
