Hi Ignacio, 

It sounds like you have a fun trip planned! Check out this article we have on the Balkans for some inspiration. I also asked our Product Specialist @Hugo V to share his top spots for nature that he has visited in the Balkans. Here they are:

• Durmitor Mountains, Montenegro. Take the train to Podgorica/Kolasin (Also Tara/Piva canyon and Kotor Bay)
• Seven Lakes in the Rila mountains, Bulgaria. Take the train to Sofia
• Belogradchik rocks, Bulgaria. Take the train to Vidin or any town close to Belogradchik
• Bugeci mountains, Romania. Take the train to Busteni/Brasov
• Fagaras mountains, Romania. Take the train to Fagaras/Sibiu
• Neretva Canyon, Bosnia & Herzegovina. Take the train to Konjic or any town towards Mostar
• Pirin Mountains, Bulgaria. Take the Rhodope Narrow Gauge line (Septemvri - Dobrinishte)

Let us know if you visit any of them! We’d love for you to share your itinerary or any photos in our Routes & Destinations Space, here. 

Enjoy your trip! 

Thank you so much for your answer it was very usefull!

Happy to help!