Alaska Bore Tide. Credit: Anchorage.net
Alaska’s Surfable Bore Tide
There’s no need to head to Hawaii’s North Shore to catch a big wave; instead, head to Alaska! Turnagain Arm, located south of Anchorage, Alaska, is where surfers come from around the world to surf the bore tide. You read that right! During bore tides, outgoing water from a river or narrow bay meets tidal waters coming in from the ocean. At high tide, a massive wave travels against the river’s current at up to 24 miles per hour and reaches heights that are often greater than the heights of ocean waves!
Why the Wave Forms
The Alaska bore tide has a difference of 35 feet between high and low tides, making it one of the most significant tidal swings in the world. A typical Turnagain Arm wave is two to three feet tall, although some waves can reach 12 feet tall. According to Travis Rector, Ph.D., a professor in the university’s department of physics and astronomy, bore tides occur because Turnagain Arm is so long and narrow that the water takes six hours to move in and six hours to move out.
Map of Turnagain Arm. Credit: FreeWorldMaps.net
Surfing the Bore Tide
All of these qualities make it particularly captivating to surfers who come from far and wide to see it for themselves. Surfers have only two opportunities each day to surf during high tide, which makes bore tide surfing a challenge for both novice and experienced surfers. Ocean surfing offers surfers multiple chances each day to catch a wave, and if one doesn’t work out, more will roll in right behind it.
Turnagain Arm surfing is a relatively new sport, with the first surfers testing the waters only a few decades ago. The sport only gained national attention recently, and it isn’t as popular as conventional ocean surfing. Bore tide surfers rely on tide charts to predict when and where the tide will hit from one day to the next. At the new moon and full moon, tides are at their highest due to gravitational forces generated by the sun and moon. For surfers, the new and full moon phases of the month usually provide the best tidal bores.
As well as Turnagain Arm, bore tides exist all over the globe, from the Bay of Fundy in Nova Scotia to the Qiantang River in China, where it is called the “Silver Dragon.” But the Alaska bore tide is by far the most spectacular!
Sources and Further Reading
- Alaska Turnagain Arm bore tide references
- Surfing and bore tide references cited in the article
