Records of tsunamis go back thousands of years and occur all over the world. Some scientists even believe a tsunami caused the destruction of Atlantis.
A tsunami is a wave, or a series of waves, caused by some activity on the seabed or at the surface. They can be hugely destructive to life on Earth.
Submarine volcanoes are found deep on the ocean floor. They can erupt just as violently as volcanoes found on dry land.