Picture a 1m high wave with a crest to crest wavelength of 100km. That is pretty much what an open water tsunami looks like. This is why when there's a tsunami

Picture a 1m high wave with a crest to crest wavelength of 100km. That is pretty much what an open water tsunami looks like. This is why when there's a tsunami warning, boats are supposed to leave the harbor, where it's dangerous, and get to sea where they won't notice the wave.