A recently found and released video of the 2011 Japanese tsunami has got to be seen to be believed. I generally don't watch clips longer than a few minutes, but what this one illustrates is just how unbelievably long the tsunami advances. I can think of no other way to show this than actually seeing that duration. And there are some cuts, so it's not clear if we're actually seeing the whole thing.
The first arrival is about 3 minutes in, and at first it doesn't look all that bad, though the boats being swept up and along are dramatic. Obviously, the onlookers are unimpressed at first, as well; they're remarkably nonchalant. Then it gets worse.
Then it gets much worse.
And by the end, it's catastrophic.
I white-knuckled my way through it, and any geo-inclined readers are advised to do the same. The educational value of this clip is incredible.