Small enough to drive across in a few hours but diverse enough to encompass the Alps and the Mediterranean, Slovenia is Europe’s most sustainable playground. Its capital, Ljubljana, is a car-free sanctuary of leafy riverbanks and emerald-green bridges designed by Jože Plečnik. The crown jewel is undoubtedly Lake Bled, where a fairytale church sits on a tiny island surrounded by the Julian Alps. Adventure seekers flock to the Soča Valley, famous for its startlingly turquoise river and white-water rafting, or descend into the colossal chambers of the Postojna Cave. With over 60% of its territory covered in forest and a burgeoning world-class wine scene in the Goriška Brda region, Slovenia is the ultimate destination for "green" travelers seeking harmony with nature.