 It contains the Cheddar Yeo, the largest underground river system in Britain.The initial sections of the cave, previously known as Sand Hole, were accessible prior to the 19th century.Between 1892 and 1898 a retired sea captain, Richard Cox Gough, who lived in Lion House in Cheddar, found, excavated and opened to the public further areas of the cave, up to Diamond Chamber, which is the end of the show cave today.