

Thermodynamics? What thermodynamics? If it gets hot just use nethercap refrigerate it. /s
IIRC one of the US nuclear apocalypse bunkers is built over an underground river, as much for the heat discharge as for the water. After that by far the biggest PITA is farming, although if you’re not expecting decades you can do cans in a much smaller area.
(Side note, you play DF?)























IIRC they were talking about this with operation Midnight Hammer, if strike one didn’t do it. I’m guessing there’s a point of diminishing returns once the hole gets deeper than it is wide, though.