Extreme cold, depth, and pressure shroud a vast area of the ocean in mystery, withholding answers to such fundamental questions as what the Earth is made of—and how human activities are changing it. You may recall pictures of a sliced-open planet, revealing a layer cake of molten rock below our feet. Research has since revealed that when superhot seawater percolates through rocks below the ocean crust, the methane produced by that reaction might provide microbial life with a potent energy source. “These extreme environments tell us about the limits of life on Earth, but the only way to get to them is with a drill.”The next frontier in the search for life at the extremes is to go deeper—much deeper. Reaching 2,500 meters (8,200 feet) is a daunting task for even the most advanced ocean drilling technologies, not to mention an exorbitant expense.