What Causes a ‘Tsunami’ and How Is It Different From a Regular Wave?

A tsunami starts when something really big shakes the ocean. Imagine dropping a stone into a pond, it makes ripples that spread out. A tsunami is like that, but instead of a small stone, it's an earthquake under the sea, or maybe a volcano erupting or even a landslide. These things push water up very suddenly and far away, making waves that grow bigger as they move toward land. Regular waves are just from the wind, much smaller and less powerful.