Most people don’t think of “life” thousands of feet under the icy continent of Antarctica. But in 2011, living bacteria were found in core samples from Antarctica’s Lake Vostok—waters lying 12,100 feet (3,700 meters) below the ice. In 2013, other evidence of life was found 2,624.7 feet (800 meters) under the ice sheet that covers Lake Whillans in Antarctica. Scientists found cells containing DNA (deoxyribonucleic acid) in the subglacial lake—cells that were actively using oxygen. Although some scientists believe the cells were from contamination by the surrounding ice, the scientists who discovered the cells cited two main reasons to support their claim: the water contained cell concentrations about one hundred times higher than the cell count in the glacier’s meltwater, and the minerals in the lake water were at least one hundred times higher than the glacier’s melt-water. The scientists also estimated that the water in the subglacial lake—and thus, the cells—had probably been cut off from the surface for 100,000 years.

An extremophile is an organism capable of surviving extreme environments. In fact, scientists continue to discover that life can inhabit many zones—from beyond the boiling point of water, below freezing, under extreme radiation, around 2.5 miles (4 kilometers) underground, and over 6 miles (11 kilometers) below sea level. For example, in 1977, scientists aboard the research submarine Alvin discovered life far below the ocean surface where no light penetrates. It was shown that the volcanic vents supplied enough nutrients for life to thrive without sunlight in a process called chemosynthesis (the ability to convert chemicals into food). These extremophiles—some bacteria and animals— thrive in temperatures above 212°F (around 100°C), the boiling point of water; some bacteria can survive even higher temperatures. Still other “extreme” bacteria can survive in oceanic pressures 6.84 miles (11 kilometers) under water, while still others survive arid, frigid, or even acidic environments. Bacteria are not the only extremophiles —in 2012, scientists mimicking Martian conditions in the Mars Simulation Laboratory in Germany found that lichens could survive for at least thirty-four days (the length of the simulation) on the Red Planet.