I saw the most wildlife of the trip on my fourth day in Costa Rica.
The view of the volcano was clear for a few minutes after I got up at 6 am! There were 13 other people on the bus to Caņo Negro Wildlife Refuge.

Our first stop was alongside the road to see a sloth in a tree.  We also stopped in the town of Muelle for a bathroom stop (since the ride to Caņo Negro is 2.5 hours) at Centro Turistico Las Iguanas.  And yes, the bushes and trees had live iguanas in them!

There were so many iguanas!  I had never thought of them in trees until this stop.  Neat! Not all of the iguanas were green.  This one was striped!
The road was very, very rough along the way.  Once at our destination, we had fresh-cut pineapple and watermelon (WOW!) while waiting for the boat. We all then got on the boat.  Much of the boat was covered, which was great, as it rained very hard for part of the trip.  The river is the Rio Frio.
I alternated between sitting and standing throughout the trip. We saw tons of caimans along the trip!
Anhingas were everywhere! We saw gray-necked wood rails, tiger herons, and this, an old friend from the US: a green heron!
The trip was so much fun!  So much wildlife to see!  (Glad I brought my binoculars!) It's not the greatest photo, but we saw this ringed kingfisher.
There were lots of turtles and caimans along the river. We also got to see this Jesus Christ lizard!
This was my best view of howler monkeys the whole trip--a tree full! I was even the one who spotted this roadside hawk!
These people canoed by during the rainstorm. One last wildlife sighting: a great potoo ("stick bird") and its baby!
We arrived at Los Chiles, near the Nicaraguan border. We ate lunch at Heliconia, about two blocks from the boat dock.
Here's a panorama of the restaurant.
This was where I had my first casado, Costa Rican plate meal: fish (others chose beef or chicken), black beans, white rice, lettuce and tomato "salad," friend plantains, half of a hard-boiled egg, a pink beet-y salad, and a pineapple-y "natural drink."  Yum--I ate it all! The weather was clear, as was the view of the volcano, when we got back to La Fortuna.
It was back to my favorite Taco's Serrano for dinner, but I had the quesadilla meal this time.
All my tours around Arenal were great!  I just wish I had planned more.  There was a lot of down time.