This was my first time zip lining, and I was a bit apprehensive. But the guides were very reassuring, patient, and everyone in our group (even those who confessed they were afraid of heights on the car ride over) enjoyed themselves immensely.
Layers are important if you go at this time of the year. There is an opportunity to have tea or a hot chocolate to warm up before you suit up. Because there are six lines to cross with different lengths, they give clear directions on how to enjoy the rides and it helps to raise your confidence level for the next one. It's pretty amazing to be a midst the tall trees with snow capped mountains in the background. In between, there was hot chocolate waiting for us before we continued.
At the end, you rappel to the ground at a comfortable speed. I had this huge feeling of accomplishment afterwards. Driving from Seattle in the carpool lane only took about an hour.