GREEN SPRING. DEEPEST CAVE IN LITHUANIA

The unique mineral water spring and the deepest cave in Lithuania have been awarded the name Green Spring. The 20 m deep cave is officially the deepest cave in Lithuania and is included in the Lithuanian Book of Records. It is a state-protected natural heritage site. Green Spring is located on the left bank of the River Lėvuo in Pasvalys. The spring started flowing from the cave after the sinkhole opened. The erupting groundwater has carved out a floodplain channel several metres long, the bottom of which is covered with a light grey, slightly greenish sediment that gives the spring water a greenish tinge. The springhead in the underwater cave is about 5 m in diameter and 21 m deep, ending in a barrier of rocks and debris, beyond which the cave splits into two chambers: the “Sunny” and the “Aenigma” (Latin for secret). The water does not freeze at the surface because the source in the cave maintains a constant temperature. That’s why the temperature of the Green Spring is 8 °C in both the hottest and coldest seasons. The story goes that at the time of the spring’s opening, there was a small barn, and one night, water suddenly started flowing into it. People pushed stones into the hole to stop the water, but the hole could not be closed.