Trenta is the upper valley of the Soča, the river that runs emerald green out of the Julian Alps, and arriving here from the Vršič hairpins feels like being let out into a quiet room. The mountains rise on both sides, the road runs gently beside the water, and the villages are small clusters of stone and wooden houses scattered among meadows and larch woods. It lies inside Triglav National Park, Slovenia's only national park, and the whole area has the air of a protected landscape: clean, calm and generously green.
The valley's most famous visitor was Julius Kugy, a mountaineer and botanist from Trieste, who spent much of his life exploring these peaks in the late nineteenth and early twentieth centuries and wrote lovingly about them. A monument to him stands in the village. There is also a small botanical garden devoted to Alpine flora, and a visitor centre explains the geology and wildlife of the park. Chamois and ibex live on the high slopes, and the river holds marble trout, a native fish with a distinctive pattern.
The Soča itself is the star. It rises from a spring high in the mountains and flows through narrow gorges and wide gravel beds, and its colour, a clear turquoise-emerald, comes from limestone dust and the cold water. In places you can stop beside a bridge and look down into pools so clear that you can count the stones. The air is cool and fresh, with a smell of pine and river stones, and in autumn the larches turn gold.
The road through the valley is a delight, a gentle descent after the intense hairpins of the pass, with smooth surfaces and easy bends, though it narrows in places and caravans can slow you. In wet weather the valley collects cloud and rain, and in summer there is heavy traffic on weekends. Early morning gives the best light and the most solitude.
Facilities are limited. A few guesthouses and small cafés serve trout, polenta and hearty soups, but shops are few. Fuel is in Kranjska Gora, on the far side of the pass, or in Bovec down the valley, and it is wise to fill up there before you cross. Bring cash, as small places may not take cards, and give yourself time to linger.