You want to look for glass frogs? The greatest diversity occurs around the Andean slopes of Colombia and Ecuador but getting there takes some dedication. Costa Rica is an easily accessible tourist friendly country with many cool species of glass frogs. A friend of mine, Brian Kubicki, wrote Glass Frogs/Ranas de Vidrio of Costa Rica. Get his book. Then look up his place – the Costa Rican Amphibian Research Center. Brian purchased 45 hectares of prime Atlantic slope property where he preserves and studies a number of threatened amphibian species. Brian’s specialty is glass frogs. If you contact him you might be able to arrange guide service and visits to his place and see first hand these really cool little frogs.
My only South American glass frog, Nymphargus siren, from the Rio Napo, Ecuador.
You can also visit Rara Avis. This reserve has comfy rooms and lots of trails cutting through secondary and primary rainforest of Atlantic Slope Costa Rica. I’ve spent a lot of time there with the 3-4 species of glass frogs they got hopping around. And when was the last time you had a tractor take you to your ‘hotel’?
Also, the Atlanta Botanical Gardens amphibian research division is working with some species of glass frogs. You might be able to see some at their facility.
If you want some more info, such as locations or reference publications, then post a comment and I’ll reply.