Mars is now a cold, dry planet, but it was once wet, warm, and may even have oceans. In the early days of Mars's formation, it was likely that Mars had oceans. Among the eight planets in the solar system, Mars is another planet other than Earth that once had oceans. In the early days of Mars's formation, the ocean may have covered most of its surface. If all this water was released to the surface of Mars, it could form an ocean 6 to 300 meters deep. Due to the rugged surface of Mars, this water creates huge surface runoff on the surface of Mars. For example, in the history of Mars, the Strait of Casei Wallis was 50 to 150 kilometers wide and 18 kilometers deep. Its drainage capacity is twice that of the Strait of Gibraltar and is now the largest river on earth. -10,000 times the Amazon River. But due to Mars 'relatively small gravity and the ionization of solar radiation, the oceans on Mars quickly disappeared.
Scientists speculate that about 1 billion years after the formation of Mars, there were no oceans on the surface of Mars, but there were still teardrop-like current structures in some areas. On the surface of Mars today, solid water (ice) can only be found at the poles, a few volcanic craters, and permafrost near the surface. According to the principle that life can only be found with liquid water, life can only be found. The current detection results are that liquid water may only exist in the deep crust 2 to 3 kilometers below the surface of Mars.