> That's interesting. Mental note, if piloting a vessel in a tsunami, head to deep water.

E.g. the 2011 tsunami may have had a height of 1.2m or so in open ocean, but when concentrated by shallower water and a bay inlet reached 40m.

Here's a visual of your thoughts from the Fukushima event:

https://m.youtube.com/watch?v=-VcWF8dIDj4

Japan, Tsunami. Coast Guard ship rides over the tsunami waves. 日本 - 津波 4.1M views · 14 years ago

Neat video. It seems to capture the middle between "super high coastal wave" and "shallow but long duration wave in deep water". That's what you'd get with coastal waters several tens of meters deep.