Ponerёtka River is an underground river in Borovichi district of Novgorod region. It is a left tributary of the river MSTA. The unique natural heritage. Ponerёtka flows into Mstu in Borovichi thresholds. Presumably, the name of the river came from the word "Ponor". It - depression in the ground where the river hides a few kilometers before the confluence of Mstu. Ponerёtka originates in Lake Lanёvo flows through the village Vishma.

The picturesque hilly area in the region is rich in various manifestations Ponerёtki karst and is a one-piece, and a mobile scale karst complex, which is associated with limestone Serpukhov suite. It consists of a basin with Ponor Lucky in tract, in which completely go Ponerёtki water, and a dry, overgrown forest and sod, river valley about 2 km long, which ends at Msta canyon with steps waterfalls former.

Underground channel and delta Ponerёtki are unique objects for the hydrogeological study of karst. It is not known so far, where there are almost 2 km flooded underground riverbed and why the current direction, contrary to the laws of physics, is located 600 m upstream Msta. Its root shore between 2 umya mouths covered with sinkholes and outs of groundwater.

Cave, also known as Ponerёtkoy developed in limestones of Carboniferous. It is one of the largest caves in the central part of the Russian platform. But it is a little research is available. Cavers underground cave were found various manifestations: the moves, manholes, siphons, halls, lakes, cliffs and even a gallery length of tens of meters and a height of human growth. At present, the length of the passages of the cave is 1420 m, while the area mapped the maze is a small rectangle about 200h250m adjacent to the shore Msta. The depth of the cave is 4 m, category of complexity - the second.

About cave Ponerёtka a lot of rumors and legends. Legend tells that long ago flowed on the surface of the river and on its banks were people who knew neither evil nor evil. But one day they decided to hide from the world, because there was evil, it was multiplied and disaster hangs over them and their houses. And in order to hide from people, they have gone underground and brought along the river. Now the spirits who lived on the river people live in the walls of caves and hate to re-emerge into the light.

The cave entrance can be seen at 400-500 m above the confluence of the dry riverbed in Ponerёtki Mstu. It is a 2 low (70-80 cm) deeper into the coastal cliff Msta from which follows the river. The cave is only available in the summer or winter low water in the bitter cold. The cave is inhabited by bats.

Water Ponerёtki waterfalls pour from a 2-O cave, located in the vertical rocky outcrop left steep bank of almost 3 m above the low water level of the river MSTA. This place is unique hydrological and aesthetic object. In addition, it is widely known and attendance not only locals but also tourists.

Water comes out numerous flow on the left bank and riverbed Msta below the mouth. In addition, in the tract are Klyuchko pressure keys. In the area there are Ponerёtki extensive karst fields that are saturated and subsidence craters of different sizes. Near the village and the Maryinsky in the woods east of the village located Elekovo most pronounced funnel.

Underground River Ponerёtka very popular among fans of extreme kayaking, as the river kilometer zone from the cave is available for playing kayaking.