Researchers say water on the planet's surface was formed as a result of interactions between the Earth's ancient atmosphere and the magma that covered its surface early after its creation. When it arose, Earth was not as calm blue as the oceans it seems today, but a huge mass of extremely hot magma, before gradually cooling down over tens of millions of years and forming the atmosphere and oceans.
Researchers say other hypotheses about where water comes from on Earth are still possible, but they are not enough to explain the presence of all this amount of water on our planet.