The largest submarine wave ever to be recorded occurred on March 28, 2001 off Palau, resulting in no devastation at all, at least on land. It was a wave of seawater having a different temperature from that which it impacted. It could more accurately be called a deep-water internal wave, and occurs at the interface of two different densities of water (as determined by temperature). A good local example in microcosm is sometimes to be found in the Kaitoke wetland or swamp, where clear seawater intrudes two to three kilometers into the swamp, but is overlain by colder fresh water. At the interface one can see wave-like disturbances quite clearly, in the event I saw, it was 30cm beneath the top water surface.

Don Armitage (copyright 2008)