“The IceCube detector, which became operational in 2010, is the largest of its kind. The observatory can monitor 1 billion tons of the Antarctic ice for neutrino interactions. To build the detector, workers drilled 86 holes in the ice, each 1.5 miles (2.4 kilometers) deep, and spread a network of 5,160 light sensors over a grid that spans 0.2 cubic mile (1 cubic kilometer).”

Holy shit. I hadn’t heard of this thing, but that’s an amazing solution.