The follow info from: http://www.alaska.org/advice/alaska-bore-tide
What’s So Special About the Turnagain Arm Bore Tide?
Well, it’s huge—one of the biggest in the world, actually. Also, all other bore waves run up low-lying rivers in more southerly latitudes. The Turnagain Arm bore wave is the only one that occurs in the far north and the only one bordered by mountains, making it the most unique and most geologically dramatic bore tide in the world. It’s also amazingly accessible: you can see it by road along its entire 40- to 50-mile length. And it’s a wildlife-spotting opportunity: harbor seals often ride the tide into Turnagain Arm. Beluga whales may come in a half hour or so later once the water gets deeper.