The Big Hole, Open Mine, Kimberley Mine or Tim Kuilmine (Afrikaans: Groot Gat) is an open-pit and underground mine in Kimberley, South Africa, and claimed to be the deepest hole excavated by hand, although this claim is disputed.

The first diamonds here were found by Erasmus Jacobs on Colesberg Kopje by members of the “Red Cap Party” from Colesberg on the farm Vooruitzigt belonging to the De Beers brothers, in 1871. The ensuing scramble for claims led to the place being called New Rush, later renamed Kimberley in 1873. From mid-July 1871 to 1914 up to 50,000 miners dug the hole with picks and shovels, yielding 2,720 kilograms (6,000 lb; 13,600,000 carats) of diamonds. The Big Hole has a surface of 17 hectares (42 acres) and is 463 metres (1,519 ft) wide. It was excavated to a depth of 240 metres (790 ft), but then partially infilled with debris reducing its depth to about 215 metres (705 ft). Since then it has accumulated about 40 metres (130 ft) of water, leaving 175 metres (574 ft) of the hole visible. Once above-ground operations became too dangerous and unproductive, the kimberlite pipe of the Kimberley Mine was also mined underground by Cecil Rhodes’ De Beers company to a depth of 1,097 metres (3,599 ft).

Since the early 2000s, an effort to register the Big Hole as a World Heritage Site has been underway.