An Ocean On Planet Mars?

Sediments reminiscent of an ocean floor was detected within the boundaries of previously identified ancient shorelines of Mars.The research argues that there were possibly two oceans on Mars, the first one four billion years ago when the conditions were warmer, and the other three billion years ago. The more recent ocean would have been there for a million years. The water then would of frozen back in place, and preserved underground again...or turned into vapor and lifted into the atmosphere.The new research gives a new understanding of the mysterious red planet, that was once possibly blue...yet the question remains where did all the water go?