Cserszegtomaj Wellcave, Natural cave formation in Cserszegtomaj, Hungary

The Cserszegtomaj Wellcave opens 50 m down the concrete wall of a 64 m well in the village cemetery, at the contact between Triassic dolomite and Miocene sandstone. Its passages stay nearly horizontal, with only 12 m between the highest and lowest points, yet the maze runs over 3300 m while spanning just 146 m east-west and 125 m north-south. Walls of quartzite sandstone carry gypsum, red, blue and black hematite and manganese coatings, and 5–10 cm limonite stalactites.

The cave was found by accident in 1930 during well digging at the Cserszegtomaj cemetery; the first written mention is in a manuscript by geologist Rozlozsnyik Pál. In 1931 a German university professor took its Gothic-like pillars and vaults for an ancient casemate. Szentes Ferenc surveyed it in 1947, and in 1965–1966 the Toldy Ferenc school's caving group raised its length to almost 800 m.

The cave has been called Cserszegtomaji-kútbarlang in literature since 1977; earlier names include Kút-barlang, Dornyai Béla-barlang and Cserszegtomaj's Well Cave. Its largest chamber is named after geologist Szabó Pál Zoltán, who is honoured with a memorial plaque there. In 1931 a visiting German professor mistook the Gothic-looking pillars and vaults for an ancient artificial casemate.

The cave opens 50 m down the 64 m well shaft in Cserszegtomaj's cemetery, inside the concrete lining. It is closed, so entry needs a permit from the Balaton-felvidéki National Park Directorate and prior cave-travel experience. Bring an electric lamp: carbon dioxide reaches 4.1% in the far Southern Section, and the passages are mostly crawled on all fours.

Air temperature inside is 12.5–12.8 °C, above the Hungarian cave average, and carbon dioxide reaches 4.1% in the farthest part of the Southern section. Ventilation happens only through the entrance shaft, so CO2 rises with distance from it. Electric lamps are required because of these gas levels.