In 2018, the European Space Agency’s Mars Express orbiter found the first evidence for an underground lake on Mars. The lake was deep below the south polar ice cap. What an exciting discovery! Then, in 2020, space scientists reported that they’d discovered three additional lakes near the first one. Any lakes on Mars, even if cold, salty and dark, would increase the potential for some form of life existing on the Red Planet. But are Mars’ subsurface lakes really lakes?