I thought I had read at some time that they had found bacteria down to like 10,000 meters or so. Some site in Norway?? Ring a bell, anybody??
The Siljan Ring drill project was in Sweden, and that was one of Thomas Gold’s experiments in this field. Here are the URLs I have of his formerly online papers, those interested can probably find them via the Webarchive.
http://www.people.cornell.edu/pages/tg21/assoc.html
http://www.people.cornell.edu/pages/tg21/DHB.html
http://www.people.cornell.edu/pages/tg21/depth.html
http://www.people.cornell.edu/pages/tg21/Earthq.html
http://www.people.cornell.edu/pages/tg21/eyewit.html
http://www.people.cornell.edu/pages/tg21/hazard.html
http://www.people.cornell.edu/pages/tg21/index.html
http://www.people.cornell.edu/pages/tg21/Krop.html
http://www.people.cornell.edu/pages/tg21/metal.html
http://www.people.cornell.edu/pages/tg21/Natgas.html
http://www.people.cornell.edu/pages/tg21/origins.html
http://www.people.cornell.edu/pages/tg21/recharging/
http://www.people.cornell.edu/pages/tg21/usgs.html