When we visited Costa Rica a couple of years ago, the must-do in our list was ziplining thru the cloud forest of Monteverde. Imagine flying through the air (it seems) above the treetops and in the last course was a 1-km ride thru dense fog. Can get scary knowing you’re hanging on dear life and all you see is nothing.
You want more action? The course has 15 cable lines made of steel and 18 platforms. In order to get to the next platform one must hike. The path is paved and snakes throughout the forest and goes up and down.