A two storey, branched and very beautiful cave. The entrance has dimensions 2×2 m. A heavily inclined entrance gallery leads to the first area of blocks. After this area is the largest chamber in the cave. It is 40-50 m long and 17-18 m wide. The main gallery is 4-5 m wide and at 40-50 m it narrows to 0,5-1 m. This narrowing is 7-8 m long. After the squeeze the gallery gets wider and ends in a vertical of 7-8 m, falling in the water gallery. Downstream, the gallery is 100 m long and ends in a siphon. After the siphon, the water reappears in the gallery below the terrace.
Upstream, the gallery bifurcates. The right gallery crosses the block area and we reach wide galleries, full of flowstone formations, sinter lakes, stalactites and stalagmites. The left one is poor in flowstone formations. After 50-60 m, both galleries merge together, then bifurcate again and join the main gallery, with many branches at the end. The end of the cave is a narrowing, from which an underground stream runs with a non-consistant outflow of 10-20 l/s.
The cave was partially adapted for visitors by F. Filchev.
Yubileyna was discovered during an exploration of Novomahlenska river in 1974 by F. Filchev, A. Andreev and other cavers from Peshtera town.
The fauna in the cave (studied by P. Beron in 1973 and 2005) includes the troglobite centipedes Lithobius lakatnicensis (Chilopoda) and L. stygius.