system
Given the following post, respond as if you're commenting on Reddit:
human
How deep into the earth have humans explored?

Is the Marianas Trench the deepest we have explored? Is there any caves deeper on land?
gpt
The deepest we have dug is the Kola Superdeep Borehole in Russia which went about 12 km deep. There have also been some oil wells that have gone similarly deep.The deepest known cave is the Voronya cave which is about 2 km deep.