Scientists have long suspected that Mars was once teeming with water, a tropical oasis with vast river systems that may have been able to support life billions of years ago. From there, the team inferred that the ocean the delta flowed into was at least the size of the Arctic Ocean on Earth. What implications the findings have for the search for ancient life on Mars remains unclear. But it’s an intriguing new glimpse into the planet’s ancient history when it was still teeming with water — a tantalizingly habitable spot far away from home. More on Mars: Scientists Find Evidence of Ancient Tropical Oasis on Mars