One of the best things I've done so far was hike through the jungle at night. There are tours in Manuel Antonio called "Jungle Night Tours Manuel Antonio", which brings you to the middle of the jungle on a search for night creatures, like frogs and insects.
The tour guide was passionate and knowledgable and had an amazing ability to spot everything nocturnal. I found a cyanide spitting centipede (I was pretty proud). The tour guide put the centipede up to my nose (it was huge, and they freak me out) and the cyanide spelled delicious- like almonds. We also found a giant frog that, when picked up, makes the most alarming sound in an attempt to attract larger animals, like snakes, to attack whatever has the frog. It also emits poisons from its skin that acts like pepper spray. We saw four types of frogs, 3 species of walking sticks, two species of vine snakes, and all sorts of spiders (HUGE SPIDERS).
Throughout the night, we were also being followed by something in the canopy. My mind immediately went to jaguar or puma (there aren't any of those cats in this part of Costa Rica). At the very end of the tour, we saw what was following us. We caught a kinkajou staring at us from the canopy. We were able to see her through the telescope, but we were too busy admiring her to take any photos. Kinkajous are now one of my favourite animals <3.
The two hours passed by too fast. I could spend all night running around the jungle trying to find things.
Pura Vida <3
https://en.wikipedia.org/wiki/Kinkajou