The terrain of Mars suggests that the red planet once had much more water on its surface than it does today. Some outflow channels suggest that massive floods may have rushed across the surface in the distant past. Some scientists wonder whether Mars may have had an ocean in its northern hemisphere long ago. While the word is still out on that, recent spacecraft findings have shown rocks that only could have formed in the presence of water, as well as evidence of lakebeds and other interesting features associated with water.