My boyfriend and I went on the Night Walk tour in the Rainmaker forest with Mario as our guide. We both had an amazing time on this tour. The size of the tour groups are small- only one other family in addition to us on the tour. You leave the Manuel Antonio area at around 5pm, and return a bit after 9 pm. It's not a long drive to the walk. The walk itself is very interesting- you see a lot of insects, snakes, and get to walk the suspension bridges. Very cool to be in the forest and see the beautiful stars. Mario is very knowlegable and a good teacher. This walk is quite interactive though-- you will get to find and point out animals and insects you see and point them out to Mario.
Another awesome thing about this tour is that Mario will take pictures with his camera of the animals you see and email them to you-- that way you can experience the walk and not constantly be worrying that you've captured everything on your camera. This walk is good for all ages- as long as you are able to walk for a couple hours... so maybe not young kids or others with mobility issues- but definitely recommend to everyone.
You get a bottle of water at the end of the trip- but would recommend eating dinner/snacks prior to the walk.
Recommend good walking shoes, long pants, - didn't need a jacket, but it was a bit cooler than in Manuel Antonio. Very good value for the money.