The entrance of the Duhlata cave looks deceptively small. It is secured with a door of metal bars. Photo by Wikipedia Four adults and three teenagers have been stranded in the Duhlata cave in Western Bulgaria after the torrential rains and rising underground waters flooded its lower passages.

The seven people entered the cave at about 8 pm Friday night; they are known to be speleologists. The kids are aged 11, 13 and 14, and are known to be teenage climbers. They are from Sofia, Pernik, and Karlovo.

The Duhlata cave is long 18 km and is known as the more complex underground labyrinth in Bulgaria; it has seven levels. It is near the village of Bosnek, alongside the Struma River.

The cave is secured with a door of metal bars but the speleologists received the key for the door from the mayor of the nearby village, not expecting that the torrential rains will affect their trip.

The rescue units of experienced cave explorers are certain that the stranded people are safe because even if the low passages of the cave are flooded, it also has several higher floors where they probably found refuge.

The rescue units got a bulldozer to start smashing the rocks at the site of water springs starting at one side of the cave in order to release more water from the cave passages.