There is a grove of Square Trees or Arboles Cuadrado in El Valle. We drove there from our hotel but it's really not that far. The Square Trees are outside the Hotel Campestre and there is a sign pointing the way. This is FREE.
Apparently, this is the only known place in the world where trees
have rectangular trunks and the shape is probably due to some
unknown but purely local condition. The tree rings also are square.
So this is a very worthwhile thing to see. You will
actually hike through the rainforest and see lots of interesting plants
where there's water running through and plenty of Leafcutter ants to view.
We also went to search for El Macho, but somehow missed it! But our quest to find it proved to be a nice walk. The waterfall is actually just a short walk from the road and we are sure you can find it. You can also view it from the Canopy Zip Line ride. We passed on this. El Macho is free but you'll pay about $65 for the zipline.