Nadarska Cave, Rufinka's Grave & Gorlo Canyon

The day starts underground, at the little wild cave of Nadarska: helmets and headlamps on, a few metres down into a world of stone most people never suspect is there.

Then it comes up into the light for a gentle two-to-three-hour walk to Poprelka, the village of Rufinka, a real woman who lived here over a hundred years ago and passed into a traditional Rhodope song. At her grave a plant her mother set is still said to grow, and the path takes in the Holy Trinity church at Kremene along the way.

It ends on the water, drifting by boat through the marble slot of Gorlo Canyon, where the Arda runs dark and silent between the cliffs.