This is my wife enjoying her first zip line adventure. She is about to land on her first platform. Her smile replaces the expression on her face in yesterday's photo taken a few seconds earlier, which showed her apprehension upon taking off on her first zip line ride.
Note that she is wearing a harness around her waist and legs, attached to a very sturdy hook, that is hanging from the pulley that runs along the zip line. There is a second line for safety.
This photo also shows the braking system. Managing one's speed is important on the zip lines, but it is easy to do. If you go too fast, it will be a challenge when landing on the next platform. If you go too slowly, you will stop gliding before you reach the next platform and you will have to pull yourself along the line.
The braking system is the thick leather glove that Julie is wearing on her right hand and holding against the cable. The gloves have an extra thick leather pad in the palm so you can pull down on the cable. The friction of the leather rubbing against the cable will cause you to slow down or stop.
It is not as difficult as I have perhaps made it sound. Your weight hanging down on the long cable causes the cable to bow down a little, as you can see from the angle of the cable in the above photo. That makes it actually a little uphill and will slow you down naturally as you glide into each platform.
When you are walking in a forest near where there are zip lines, you can hear a high-pitched singing sound made by the pulleys zipping down the cables.
Julie has gone on the zip lines twice. She got so comfortable that near the end of her last ride, the guide asked her if she wanted to ride like "super-chica." He changed the harness to hang from her back so that she could ride horizontally, flying through the forest like Superman. I wish I had a photo of that, but she was with a friend who was visiting from the U.S. and they kept their cameras stowed while flying through the forest.
So if you are in Costa Rica walking in the forest near a zip line and you hear a high pitched singing sound, you may say, "Look, up in the air. It's a bird. It's a monkey. No. It's super-chica!"