Hobby tunneling: https://en.wikipedia.org/wiki/Hobby_tunneling

13 comments: https://news.ycombinator.com/item?id=36885802

6 comments: https://news.ycombinator.com/item?id=28257515

Also https://news.ycombinator.com/item?id=39245893 - The underground world of hobby tunneling (bloomberg.com) 272 points by robinhouston on Feb 3, 2024 | 164 comments