[NMCAVER] Bulgarians mapping Europe’s biggest cave

[Lee H. Skinner]

Added to the current 220km, Optymistychna, also known as 
Optimisticeskaja after the Russian spelling of its name, is now more 
than 270km long, taking the distinction of the world second longest cave 
from the Jewel Cave in South Dakota. Only the Mammoth Cave in Kentucky 
is bigger.

Full article is at:
http://www.sofiaecho.com/article/bulgarians-mapping-europe-s-biggest-cave/id_29278/catid_70