Well... First time on purpose

From the article:

But we know for sure it can be done because in 2009 a nearby Icelandic geothermal plant accidentally drilled into Krafla's magma chamber. The incident revealed important insights about the liquid state and dynamic interactions of the magma, although the drill's steel casings were obliterated in the process. On the bright side, this incursion also showed that exposing the magma chamber doesn't cause volcanoes to erupt.