It never actually got dark while we were in Alaska. Oh, there were sunset and sunrise times: officially, the sun set at about 0030 (12:30 at night), and rose around 0330, but it never actually got dark, even when the sun was “down.” (Of course, this situation is reversed in the winter, with a mere three to four hours of “light”). The effect was a little disorienting, but after a few days, I mostly grew accustomed to it. There was something peculiarly thrilling about being able to check the weather on a cloudy day and say “hey, the sun is going to come out at 2300.”
Despite the decided dearth of night, we were still able to observe some interesting lunar effects (the moon is called Selene in certain astronomical circles), particularly in the form of bore tides up Turnagain Arm (part of the Cook Inlet). We had some difficulty finding, and then identifying, the bore tide, but once we had positive confirmation that what we were seeing was, in fact, the bore tide, it was an interesting sight. Not so interesting, however, that we felt the need to do as we saw one soul doing – he was attempting to surf the bore tide (this is apparently a bit of a Thing in Alaska).
Put simply, a bore tide is when the incoming tide runs counter to the typical direction of current in a certain region, creating one or more, sometimes significant, waves. Bore tides are not uncommon, but bores significant enough to be visible are: there are only a few locations in the world where bores are consistently large enough to be clearly visible. The more extreme the tides, the more pronounced will be the bore tide, so the size of a bore tidal wave will vary depending on the spread between the high and low tides.
We estimated that the bore tide we viewed was about eight inches high – a sign mentioned that the bore tides for that place could range from six inches to six feet in total height. Apparently, the bore tides in Turnagain Arm used to be more impressive, before the 1964 earthquake altered the seafloor. After spotting it at the first viewing location, we drove along to see it from another location at a narrower point, where the tide would be more pronounced. You can time the bore tide viewing: they usually roll in about fifteen to twenty minutes after low tide. The magnitude of the tidal differential affects the extent of the bore tide, which can move at almost twenty miles an hour down Turnagain Arm. There’s a whole science around predicting when the largest bore tides will be, but even a normal one is interesting in its own right.
Maybe bore tides aren’t the most exciting thing in the world – I certainly wouldn’t say that it’s a prime reason for you to make your way to Alaska – but it was an interesting phenomenon to observe, and more significant than we expected it to be. As more for the adventure of finding and identifying the tie, this was a worthwhile experience, and I would encourage you to find a chance to see the bore tide if you’re in the Turnagain Arm area.
Lloyd's Outdoor Explorations 