You saw a bit of Turagain Arm in the Alaska Bits 3 post. In those photos taken early in the day and the sunset one much later, the tide was high. Between those shots we arrived carefully at Bird Point to take another look, a look out into the arm at low tide. You can see how low it looks here.
And we waited while the tide turned and when it turns you can see it coming. If you are there on the day of the widest range of tides in the new moon, the bore tide can be a wall of water six to seven or even more feet high moving ahead of the incoming sea. Our bore tide looked only about a foot high, but it was pretty amazing at that.
You might think it looks a bit like the waves of the ocean lapping on the shore, and it does. But it just keeps coming straight up the valley as a wall--and remember we were viewing one of the smallest of the bore tides. Can you even imagine a wall of water six feet high? Makes me think tsunami. And it marches rapidly up the valley -- about a dozen miles an hour.
And the roiling waters follow it.