The story of the hand-dug well: https://www.mybrightonandhove.org.uk/places/utilities/woodin...
Lake Baikal sediment layer almost as deep as the Mariana Trench:
https://en.wikipedia.org/wiki/Lake_Baikal#Geography_and_hydr...
[...] and below this lies some 7 km (4.3 mi) of sediment, placing the rift floor some 8–11 km (5.0–6.8 mi) below the surface, the deepest continental rift on Earth.
Explain xkcd has links to the Wikipedia articles for each hole.
I forget how cool Lake Baikal is until it shows up randomly and I'm reminded to go look it up again.
You cannot convince me that something ridiculous wasn't covered up wrt Deepwater Horizon.
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Hover text is "If you're thinking 'Wait, a giant crystal cave in Mexico? What's that?' then I'm SO excited for the image search you're about to do."