This route connects the two highest peaks in Bulgaria, located in two different mountains. Musala peak (2925m) in Rila mountain is the highest on the Balkan peninsula and Vihren peak (2914m) is in the Pirin mountains, second highest in the country. The distance between the two peaks is 77km and has 5000m D+ and 5000m D-. The average altitude is 2180m, the lowest point is 1140m - Predela pass. The terrain is mostly grassy and rocky paths along open mountain ridges - wider in Rila and much narrower in Pirin. Small part of the route goes through forests.
The original idea in the past was to connect the two highest peaks in Bulgaria in less than 24 hours. Many people did it for the challenge and few of them attempted an FKT. The fastest time was a little bit more than 21h, set in 2017 by three Bulgarian runners - again not official time and not a FKT attempt. In 2019 Kaloyan 'Kofe' Peychev made an attempt to set a fastest known time and the result was 15h29min42sec.
The biggest challenges apart of the route itself are that first you have to reach Musala peak from the small resort Borovets (12km, 1500m D+) and after reaching Vihren peak you have to descend from it along very rocky terrain to Vihren hut (at least) or the town of Bansko. This makes the whole route around 93km, 6500m D+ and 6000m D-.
The best time of the year to attempt this route is between July and late September as before that there is still some snow in the highest parts and after September the risk of ice is not to be underestimated.
--submitted by Kaloyan 'Kofe' Peychev
Note that some people have reported summit-to-summit time (as are the times above), but for FKT purposes you should report your trailhead-to-trailhead time.