When you think of giant, frightening, destructive waves, tsunamis definitely come to mind. But don't confuse these giant waves with rogues -- while both can be catastrophic, they are quite different. The easiest way to remember the difference is by what causes the "wall of water" and where the destruction from it occurs.
Tsunamis are most often caused by undersea earthquakes, which send tons of rock shooting upward with tremendous force. The energy of that force is transferred to the water. So, unlike normal waves that are caused by wind forces, the driving energy of a tsunami moves through the water, not on top of it. Therefore, as the tsunami travels through deep water -- at up to 500 or 600 miles per hour -- it's barely evident above water. A tsunami is typically no more than 3 feet (1 meter) high. Of course, all that changes as the tsunami nears the coastline. It is then that it attains frightening height and achieves its more recognizable and disastrous form.
Rogue waves, as we've discussed in this article, arise seemingly out of nowhere, and they can attain their massive heights in deep water, not just along the shoreline.