Truso Valley is where the Terek River is born — the great Caucasus river that later carves the Darial Gorge and runs north toward the Caspian. The gorge stretches about 25 kilometres between snow-streaked peaks, flat-floored and treeless, with braided river channels running down the middle. What sets it apart is the colour of the ground. Mineral springs seeping up through the valley floor have laid down sheet after sheet of ochre, yellow and rust-red travertine, so whole stretches are stained orange. Georgia protects them as the Truso Travertines Natural Monument. Beside them the small Abano lake churns and fizzes as if boiling, though the water is cold to the touch. Above it all stand centuries-old defensive towers and the ruined Zakagori fortress, watching over what was once an Ossetian highland homeland. Almost nobody lives here now — a handful of summer shepherds, and stone houses with no roofs.
Getting in is part of the adventure. A rough dirt track leaves the Georgian Military Highway near Kobi, and only a proper 4x4 can drive the full gorge. Most walkers cross the flat valley floor on foot, which takes most of a day, past grazing cattle and springs that smell of sulphur. The mineral water is drinkable, if sharply eggy. There is almost no infrastructure: one small campsite, a water tap, abandoned stone houses. It is also a sensitive place, pressed against a sealed border with Russian-controlled territory. You can hike freely only as far as Zakagori fortress, where a Georgian border post turns you back; beyond it is a restricted military zone, and in winter the guards seal the valley mouth entirely. Come on a clear summer morning, before the wind rises off the peaks.