Images from the Mars Reconnaissance Orbiter have provided evidence of possible icebergs in the ancient Martian past. It has long been speculated that the northern smoother plains were once the bottom of an ocean; now, clusters of boulders and chains of pits or craters have been found there which are very similar to those on Earth, in areas where icebergs have scraped the bottom of the ocean, depositing rock fragments.
Of course, if there were icebergs, then there must have been oceans or seas. The findings support a more recent theory, of a cold and wet early Mars. So perhaps more like the Arctic ocean rather than the tropics, but still significant in terms of possible life.