How Did the Earth's Oceans Form?

The Earth’s oceans formed when water came together in big puddles on the planet’s surface.

Imagine you’re playing with a toy boat in a bathtub. At first, there's just a little water, not enough to make a real ocean. But what if the bathtub started filling up from a faucet that never stopped? Soon, the water would rise and cover all your toys, just like how Earth got its oceans.

The Earth was once very hot, like a giant lava cake. As it cooled down, some of the heat escaped as steam, which is like invisible water vapor. This steam went up into the air and then came back down as rain, just like when you breathe on a cold window and see your breath turn into little clouds that make droplets.

At first, these rains made small puddles all over Earth. But as more water collected in low places, like valleys and basins, the puddles grew bigger and bigger until they turned into oceans.

It’s like when you spill a little water on your floor, but then someone pours an entire bucket of water onto it, suddenly, you have a mini lake!