Obrovská Abyss
It is situated on the Dolný vrch Plateau above the Jablonov nad Turňou village. This corrosive-breakdown abyss is 100 m deep. It is formed in the Mesozoic Middle Triassic pale Wetterstein limestones of the Silica Nappe. The main shaft under the surface depression widens in bottle shape downwards into an underground dome. A cone of debris and boulders is on its bottom in 63 m’s depth. One edge of the dome has an opening leading to the lower shaft more than 20 m deep. The first descend to the abyss was done by Hungarian cavers in 1959.
It is the third deepest abyss in the Slovak part of the Dolný vrch Plateau. Deeper are only the Natrhnutá Abyss (-112 m) and Hniloš Abyss (-110 m). The Hungarian side of the plateau has the deepest Vecsembűkki-zsomboly Abyss (-236 m).
Four bat species were discovered here by now, with the most abundant Lesser Horseshoe Bat (Rhinolophus hipposideros) and Greater Mouse-Eared Bat (Myotis myotis). Invertebrates are represented by rare cave pseudoscorpion Neobisium (Blothrus) slovacum, which was the first time discovered in the nearby Diviačia Abyss.