Prohodna Cave

The Prohodna Cave, located 2 kilometers from Karlukovo in north-central Bulgaria, is one of Bulgaria's largest and most accessible caves. It's a prominent feature in the Karlukovo Gorge, which is part of the Iskar-Panega Geological Park and is one of the country's greatest kart sites.

Prohodna Cave is a tunnel cave with a length of 262 meters, making it Bulgaria's longest of its kind. The Big Entrance and the Small Entrance are located at opposite ends of the building. The former is at least 45 meters high, making it Bulgaria's largest cave vault, large enough for bungee jumping. The cave's name, which translates to "Passage Cave," reflects its shape.

There are also two massive nearby holes in the ceiling that look like a pair of enormous eyeballs. This is the most well-known feature of Prohodna Cave, also known as Oknata in the locality.

Region: Lovech Province, Bulgaria