UPDATE FROM COSTA RICA
We went zip-lining, which is a sport where the object is to look like the world's biggest dork. I was very good at it.
After you get dorked up, you climb up to a platform in a tree and are hung from a cable by a cheerful guide, who sends you hurtling across the rainforest canopy, which is sometimes a looooooonnnnnnng way below. Theoretically you are admiring nature as you do this, but really you are just trying not to wet your cargo shorts. When you reach the next platform, another cheerful guide attaches you to another zip-line, and off you go again.
To do this, all we had to do was show up. If you wanted to zip-line in the United States, you would have to first spend about six hours signing lawyer-excreted waivers, then undergo extensive safety training, then wake up from your dream, because you will never be able to zip-line in the United States. Which is too bad, because it's actually fun, once you gain control of your sphincter.
While hiking up to the first platform, we encountered a poison dart frog, which we were told gets its name because the natives used to put its venom on the tips of their darts. At great personal risk, I was able to take this picture:
We also saw a pile of poop that the guide told us was from a howler monkey. But I think it might actually have been from one of the more fearful zip-liners.
Last night we ate at a restaurant with a large plane in it. We don't know how the plane got there, and we don't want to know.