Deepest shaft occurring naturally

Deepest shaft occurring naturally
Who
Vrtoglavica
Where
Slovenia (Mount Kanin,)
When
01 January 0001
Vrtoglavica (meaning vertigo) is an unbroken vertical shaft 603 m (1,978 ft 4 in) deep in Monte Kanin, Slovenia. It could comfortably accommodate two Eiffel Towers.