I had a quick search and the top result for a datacenter in a mine is in Norway https://www.lefdalmine.com/ . I grew up next to a salt mine in the Alps, and those mines are really cold places. The mine is even, by the nature of the former mining, multi-story which most overground datacenters are not. Uruguay doesn't have mines, but I sure with some creativity they could use the heat produced by the data center for other industrial processes.