nps staff

The bore tide is a spectacular and PREDICTABLE feature of Southcentral Alaska.

Alaska's Turnagain arm and Knik arm, that surround Anchorage, boasts the second highest tides in North America after the Bay of Fundy. These tides, which can reach 30 feet, come in so quickly that they sometimes produce a wave known as a bore tide wave. Adventurous locals have taken to riding this wave out on a kayak or board - talk about extreme surfing!

The best place to see the Alaskan bore tide is along Turnagain Arm, just south of Anchorage. In particular, Beluga Point, Indian, and Bird Point are easily accessible by road and are within an hour drive of Anchorage. Bird Point offers a small interpretive panel dedicated to the tide.

Bore tides exist in other places around the globe such as the Bay of Fundy in Nova Scotia, and the Tsientang River in China. The longest exists in the Amazon River in South America - there too, extreme surfers dare the wave on a 99 mile stretch of water.

CAUTION! Our bore tides are dangerous. Due to the quicksand-like mudflats that make up the beaches along Turnagain Arm, hikers may get stuck in the mud and drown or die from hypothermia. Always stay off the mud flats and observe the bore tide from a safe distance.

While Turnagain arm boasts the highest tides in the United States, the honor of highest in North America belongs to the Bay of Fundy pictured above.

Bore Tides 2011 (a PDF) and Bore Tides podcast with Ranger Roger (a MP3)
It's pretty easy to predict when the bore tide will hit a given point if you know when low tide in Anchorage begins:

• The first thing to take note of is that an average tide, without any wind, travels roughly 10-15 miles per hour.
  
  
• Next, realize that wind plays a factor - a westerly wind means an earlier arrival, while an easterly wind means later.
  
  
• Arrive at least half an hour before the predicted the tide will arrive; bore tides do not operate like alarm clocks.
  
  
• If you reach a point and the water is already rising, the bore has passed. Drive up to the next point and check again - water will be calm immediately before the tide comes in.
  

Finally, here are some times for specific areas when the bore tide typically arrives after low tide in Anchorage:

• Beluga Point: 1 hour 15 minutes
• Indian Poin: 1 hour 30 minutes
• Bird Point: 2 hours 15 minutes
• Girdwood: 3 hours

The best times to see a good bore are when the low tide in Anchorage has a high negative value, particularly if the good low tide is followed by a good high tide; this maximizes the "sloshing" effect that causes bore tides to occur.

The bore tides are a must-see experience in Southcentral Alaska, as they occur in so few other places in the world. Be sure to enjoy this phenomenon from a safe distance, however, as they can be quite dangerous (see audio below) due to their height and speed of approach in addition to the mudflats mentioned above. Be safe, and enjoy!