Hiking around Borovets
The Yastrebets hotel (4hr 30min walk or 35min by gondola) is the starting point for the ascent of Mt Musala, the highest peak in Bulgaria (2925m). The first leg (1hr) brings you to the Musala hut at the foot of the mountain, whence it's an hour and forty minutes' walk to the summit. From Mt Musala it's six hours' trek southwards to the Granchar hut, where one path leads down to Yakoruda on the narrow-gauge railway line to Bansko; the other to the Fish Lakes (5hr) where, after sleeping at the Ribnite Ezera hut, hikers can push on to Rila Monastery (5-6hr).
If these sound too much effort, you could try an easy, ninety-minute walk to the Black Rocks (Chevemi skali), east of Borovets. A row of crags with sheer drops on both sides, they were used by the secret police in the late 1940s as a killing ground for "enemies of the people", who were simply pushed off to their deaths. The trail begins after the Hotel St Ivan Rilski, entering the woods beside a cross-braced fence. Bear right at the fork 100m later, then left down hill and left at the next fork; when you reach the farm buildings take the middle, gravelled route and turn left at the fork onto a sandy track that gets narrower and stonier en route to a picnic area near the Black Rocks.