Hidden ocean on Mars: Researchers suggest water could be 20km beneath the surface Al Jazeera EnglishUnderground reservoir on Mars could fill oceans on the planet’s surface, study finds CNNNew hope of finding life on Mars after indication of water, scientists say The GuardianNew study suggests ocean of water lies beneath Mars’s surface Al Jazeera EnglishLiquid water could abound in Martian crust, seismic study suggests physicsworld.com