There are a lot of guides at Manuel Antonio Park, but I wouldn't be surprised if Mario Brenes is the best one. It is obvious that he just has a passion for animals - and that passion drives him to know everything he can about as many animals as possible.
When we were on the tour with Mario, we saw another guide point out a frog. The guide told his 8 guests that he couldn't tell the exact species of the frog, but it could be this, this, or that. Mario took a look, and told us exactly what kind of frog it was (which was not one of the options the other guide thought it was), and proved it to us by showing us a picture in one of his many animal guide books.
Mario also has the sharpest eyes. Sometimes he would spy animals that even the other guides could not find - often times, they would have to look through his scope to find the animal so they could point it out to their own guests.
Despite the fact that I felt that Mario was doing such a better job on our tour than other guides I noticed around the park, Mario never hesitated to help the other guides out - if he found an animal, he would readily tell the other guides where it was, what type of animal it was, etc.
Mario knows so much about animals. For him, the tour through the Manual Antonio National Park is not just about finding the animals, but teaching you about them. How they live, what is unique about them, how they have evolved and survived. Other guides seem to just point out the animals and tell you a little bit about them. With Mario, you feel like you're watching a personalized episode of the Discovery Channel. He has a passion for all animals - from the tiny fire ants at the entrance (which I am really glad he told us about! that was a good thing to know) to the teeny lizard completely camouflaged on the branch, he made each animal sound so totally unique and fascinating.
Lastly, Mario is just a great guy and very proud of his business. On the day of our tour, his baby boy was sick and he told us he contemplated canceling our tour, but ultimately decided against it since he takes so much pride in the business he has built and wanted to fulfill his commitment. He talks about his family with even more passion than he talks about the animals. He is just the type of guy you want to succeed in the world, and I am extremely happy we decided to take Mario's tour of Manual Antonio National Park. I only wish we had time to take more of Mario's other tours!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.