There is no doubt about one thing. According to the information available, Mars had canals, rivers and lakes, and the ocean covered the northern hemisphere by studying the surface. The only doubt left is where the water has gone.
One billion years ago, Mars had a magnetic field, atmosphere, ocean and lakes. The magnetic field of Mars was lost over time for some unknown reason, and strong solar radiation penetrated the weak atmosphere and began to slowly dissolve into the atmosphere.
So for years it was thought that all the water behind the poles left some water and went into space. But the most plausible theory now is that only a small amount of water went into space at this time, and most of the remaining water dissolved in salts with the crust and poles of Mars.
It is also supported by information provided by the old Odyssey and the current Orbiter. So all the current information points to the fact that Mars was like this four billion years ago. Or if they were four billion light-years away, it would mean that Mars would be in this state, close to the Sun they see now.