Researcher radar scans have revealed a reservoir of salty, liquid water a mile beneath the planet. Which they believe to be a lake wthat sits under the planet's south polar ice cap.
What's even more exciting, this lake is likely not the only one on the red planet.
Previous research found possible signs of intermittent liquid water flowing on the martian surface, but this is the first sign of a persistent body of water on the planet in the present day.
Lake beds like those explored by Nasa's Curiosity rover show water was present on the surface of Mars in the past.
The newly discovered reservoir on Mars stands at 12 miles wide.
However, the planet's climate has since cooled due to its thin atmosphere, leaving most of its water locked up in ice.
The result is exciting because scientists have long searched for signs of present-day liquid water on Mars, but these have come up empty or yielded ambiguous findings.
“There are other areas that seem to be similar. There’s no reason to say this is the only one,” Elena Pettinelli an astrobiologist at Italy’s Roma Tre University said.
This discovery could yield extraterrestrial life forms.