I'm a geologist so I wasn't going to pass up the chance to see the recently active Poas Volcano! I loved the drive there, about an hour and a half through the lovely Costa Rican countryside, with a great guide who pointed out features of interest and clearly loved her country and job. Poas is that rare active volcano you can drive to the top of, and it was beautifully cool up there, about 60-65F. It tends to sock in at about 10 AM, and we got there at 9.45, but there wasn't a cloud to be seen, and we had GORGEOUS views. (Our guide later told us that in her 100s of trips there, she had rarely seen it so clear and beautiful.) It's an uphill hike of about 15 minutes or so on a wide paved road. Our guide gave us lots of free time here to move at our pace, and several of us made the hike to an older caldera, now filled with water and set in the cloud forest - gorgeous, but a more difficult uphill hike that took about 20-30 minutes for most people. There's a pricy gift shop with some nice items, and a tiny museum with limited info on the geology. The restrooms tend to get crowded; I'd stop when you first get there.
We had a great included lunch at a local restaurant (i.e., locals were eating there) - my vegetarian self was happy with the plantains, rice and beans, and delicious strawberry smoothie! The lunch was handled very efficiently and we got out of there reasonably quickly.
Then we drove via the metal church at Grecia (no stops, just viewed it out the moving bus windows) to Sarchi, for a stop at an ox-cart painting workshop. This was really a shopping stop, but I didn't mind, because the workshops were open, and one painter was at work. If you're looking for hand-painted Costa Rican souvenirs, it would be a good place to pick some up. We drove by the "world's largest ox-cart" but didn't stop. We made one last stop, at the group's request, for some candy/coffee shopping, at a very reasonably priced place with a good selection.
I would have preferred a few more actual photo stops (instead of just driving by things) - hence 4 stars rather than 5 - but overall I enjoyed this well-organized excursion tremendously, especially since we were VERY lucky with the weather at Poas Volcano - many people who go there don't get to see into the crater at all.
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